diff --git a/alonzo/test/test/Test/Cardano/Ledger/Alonzo/Trials.hs b/alonzo/test/test/Test/Cardano/Ledger/Alonzo/Trials.hs
index b8c1108f58..409f4e32f1 100644
--- a/alonzo/test/test/Test/Cardano/Ledger/Alonzo/Trials.hs
+++ b/alonzo/test/test/Test/Cardano/Ledger/Alonzo/Trials.hs
@@ -81,8 +81,8 @@ import Shelley.Spec.Ledger.LedgerState
     UTxOState,
   )
 import Shelley.Spec.Ledger.PParams (PParams' (..))
-import Shelley.Spec.Ledger.STS.Chain (CHAIN, ChainPredicateFailure (..), ChainState (..), Event (..))
-import Shelley.Spec.Ledger.STS.Ledger (Event (..), LEDGER, LedgerEnv (..), LedgerPredicateFailure (UtxowFailure))
+import Shelley.Spec.Ledger.STS.Chain (CHAIN, ChainPredicateFailure (..), ChainState (..))
+import Shelley.Spec.Ledger.STS.Ledger (LEDGER, LedgerEnv (..), LedgerPredicateFailure (UtxowFailure))
 import System.Timeout
 import Test.Cardano.Ledger.Alonzo.AlonzoEraGen ()
 import Test.Cardano.Ledger.EraBuffet (TestCrypto)
@@ -118,11 +118,9 @@ import Test.Tasty.QuickCheck
 
 instance Embed (AlonzoBBODY (AlonzoEra TestCrypto)) (CHAIN (AlonzoEra TestCrypto)) where
   wrapFailed = BbodyFailure
-  wrapEvent = BbodyEvent
 
 instance Embed (AlonzoUTXOW (AlonzoEra TestCrypto)) (LEDGER (AlonzoEra TestCrypto)) where
   wrapFailed = UtxowFailure
-  wrapEvent = UtxowEvent
 
 -- ======================================================================================
 -- It is incredably hard to debug property test generators.  These functions mimic the
diff --git a/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/BBody.hs b/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/BBody.hs
index 4378e016e1..5c437e143e 100644
--- a/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/BBody.hs
+++ b/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/BBody.hs
@@ -22,7 +22,7 @@ import           Byron.Spec.Ledger.Update (PParams, UPIState, maxBkSz)
 import           Byron.Spec.Ledger.UTxO (UTxO)
 import           Control.State.Transition (Embed, Environment, STS (..), Signal, State,
                      TRC (TRC), initialRules, judgmentContext, trans, transitionRules, wrapFailed,
-                     (?!), wrapEvent)
+                     (?!))
 
 import           Byron.Spec.Chain.STS.Block
 
@@ -57,11 +57,6 @@ instance STS BBODY where
 
   type PredicateFailure BBODY = BbodyPredicateFailure
 
-  data Event _
-    = BUPIEvent (Event BUPI)
-    | DelegationEvent (Event DELEG)
-    | UTXOWSEvent (Event UTXOWS)
-
   initialRules = []
 
   transitionRules =
@@ -98,12 +93,9 @@ instance STS BBODY where
 
 instance Embed BUPI BBODY where
   wrapFailed = BUPIFailure
-  wrapEvent = BUPIEvent
 
 instance Embed DELEG BBODY where
   wrapFailed = DelegationFailure
-  wrapEvent = DelegationEvent
 
 instance Embed UTXOWS BBODY where
   wrapFailed = UTXOWSFailure
-  wrapEvent = UTXOWSEvent
diff --git a/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/Bupi.hs b/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/Bupi.hs
index 79a09f8856..e704796632 100644
--- a/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/Bupi.hs
+++ b/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/Bupi.hs
@@ -9,8 +9,8 @@ import           Data.Data (Data, Typeable)
 
 
 import           Control.State.Transition (Embed, Environment, PredicateFailure, STS, Signal, State,
-                     TRC (TRC), TransitionRule, Event, initialRules, judgmentContext, trans,
-                     transitionRules, wrapFailed, wrapEvent)
+                     TRC (TRC), TransitionRule, initialRules, judgmentContext, trans,
+                     transitionRules, wrapFailed)
 import           Byron.Spec.Ledger.Core (VKey)
 import           Byron.Spec.Ledger.Update (ProtVer, UPIEND, UPIEnv, UPIREG, UPIState, UPIVOTES, UProp, Vote)
 
@@ -39,11 +39,6 @@ instance STS BUPI where
 
   type PredicateFailure BUPI = BupiPredicateFailure
 
-  data Event _
-    = UPIREGEvent  (Event UPIREG)
-    | UPVOTESEvent (Event UPIVOTES)
-    | UPIENDEvent  (Event UPIEND)
-
   initialRules = []
 
   transitionRules =
@@ -72,12 +67,9 @@ instance STS BUPI where
 
 instance Embed UPIREG BUPI where
   wrapFailed = UPIREGFailure
-  wrapEvent = UPIREGEvent
 
 instance Embed UPIVOTES BUPI where
   wrapFailed = UPIVOTESFailure
-  wrapEvent = UPVOTESEvent
 
 instance Embed UPIEND BUPI where
   wrapFailed = UPIENDFailure
-  wrapEvent = UPIENDEvent
diff --git a/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/Chain.hs b/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/Chain.hs
index 7aa5f3df3c..b7b3ad52ec 100644
--- a/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/Chain.hs
+++ b/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/Chain.hs
@@ -87,16 +87,6 @@ instance STS CHAIN where
 
   type PredicateFailure CHAIN = ChainPredicateFailure
 
-  data Event _
-   = UPIREGEvent           ( Event UPIREG   )
-   | UPVOTESEvent          ( Event UPIVOTES )
-   | UPIENDEvent           ( Event UPIEND   )
-   | EpochEvent            ( Event EPOCH    )
-   | BBodyEvent            ( Event BBODY    )
-   | PBFTEvent             ( Event PBFT     )
-   | LedgerDelegationEvent ( Event DELEG    )
-   | LedgerUTxOEvent       ( Event UTXOWS   )
-
   initialRules =
     [ do
         IRC (_sNow, utxo0', ads, pps', k) <- judgmentContext
@@ -172,23 +162,18 @@ instance STS CHAIN where
 
 instance Embed EPOCH CHAIN where
   wrapFailed = EpochFailure
-  wrapEvent = EpochEvent
 
 instance Embed BBODY CHAIN where
   wrapFailed = BBodyFailure
-  wrapEvent = BBodyEvent
 
 instance Embed PBFT CHAIN where
   wrapFailed = PBFTFailure
-  wrapEvent = PBFTEvent
 
 instance Embed DELEG CHAIN where
   wrapFailed = LedgerDelegationFailure
-  wrapEvent = LedgerDelegationEvent
 
 instance Embed UTXOWS CHAIN where
   wrapFailed = LedgerUTxOFailure
-  wrapEvent = LedgerUTxOEvent
 
 isHeaderSizeTooBigFailure :: PredicateFailure CHAIN -> Bool
 isHeaderSizeTooBigFailure (HeaderSizeTooBig _ _ _) = True
diff --git a/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/Epoch.hs b/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/Epoch.hs
index 83a1e9676c..7f08ae732f 100644
--- a/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/Epoch.hs
+++ b/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/Epoch.hs
@@ -42,8 +42,6 @@ instance STS EPOCH where
   type Signal EPOCH = Slot
   type PredicateFailure EPOCH = EpochPredicateFailure
 
-  data Event _ = UPIECEvent (Event UPIEC)
-
   initialRules = []
 
   transitionRules =
@@ -59,4 +57,3 @@ instance STS EPOCH where
 
 instance Embed UPIEC EPOCH where
   wrapFailed = UPIECFailure
-  wrapEvent = UPIECEvent
diff --git a/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/Pbft.hs b/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/Pbft.hs
index 1ad560d5cd..fcd43800f9 100644
--- a/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/Pbft.hs
+++ b/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/Pbft.hs
@@ -43,8 +43,6 @@ instance STS PBFT where
 
   type PredicateFailure PBFT = PbftPredicateFailure
 
-  data Event _ = SigCountEvent (Event SIGCNT)
-
   initialRules = []
 
   transitionRules =
@@ -63,4 +61,3 @@ instance STS PBFT where
 
 instance Embed SIGCNT PBFT where
   wrapFailed = SigCountFailure
-  wrapEvent = SigCountEvent
diff --git a/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/SigCnt.hs b/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/SigCnt.hs
index b3630d2505..a042a32707 100644
--- a/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/SigCnt.hs
+++ b/byron/chain/executable-spec/src/Byron/Spec/Chain/STS/Rule/SigCnt.hs
@@ -44,8 +44,6 @@ instance STS SIGCNT where
   type Signal SIGCNT = VKey
   type PredicateFailure SIGCNT = SigcntPredicateFailure
 
-  data Event _
-
   initialRules = []
 
   transitionRules =
diff --git a/byron/crypto/test/Test/Cardano/Crypto/Limits.hs b/byron/crypto/test/Test/Cardano/Crypto/Limits.hs
index e02d14b4c1..9fdf3d556a 100644
--- a/byron/crypto/test/Test/Cardano/Crypto/Limits.hs
+++ b/byron/crypto/test/Test/Cardano/Crypto/Limits.hs
@@ -45,7 +45,7 @@ tests = checkParallel $$discover
 --   is almost certainly amiss.
 
 newtype Limit t = Limit
-  { getLimit :: Word32
+  { getLimit :: Word32 
   } deriving (Eq, Ord, Show, Num, Enum, Real, Integral)
 
 instance Functor Limit where
diff --git a/byron/ledger/executable-spec/src/Byron/Spec/Ledger/Delegation.hs b/byron/ledger/executable-spec/src/Byron/Spec/Ledger/Delegation.hs
index 0053859c44..4d972895d2 100644
--- a/byron/ledger/executable-spec/src/Byron/Spec/Ledger/Delegation.hs
+++ b/byron/ledger/executable-spec/src/Byron/Spec/Ledger/Delegation.hs
@@ -114,7 +114,7 @@ import           Lens.Micro (Lens', lens, to, (%~), (&), (.~), (<>~), (^.), _1)
 import           Lens.Micro.TH (makeFields)
 import           NoThunks.Class (NoThunks (..), allNoThunks, noThunksInKeysAndValues)
 
-import           Control.State.Transition (Embed(..), Environment, IRC (IRC), PredicateFailure, STS(..),
+import           Control.State.Transition (Embed, Environment, IRC (IRC), PredicateFailure, STS,
                      Signal, State, TRC (TRC), initialRules, judgmentContext, trans,
                      transitionRules, wrapFailed, (?!))
 import           Control.State.Transition.Generator (HasTrace, SignalGenerator, envGen, genTrace,
@@ -301,7 +301,6 @@ instance STS SDELEG where
   type Signal SDELEG = DCert
   type Environment SDELEG = DSEnv
   type PredicateFailure SDELEG = SdelegPredicateFailure
-  data Event _
 
   initialRules = [ return DSState
                    { _dSStateScheduledDelegations = []
@@ -375,7 +374,6 @@ instance STS ADELEG where
   type Signal ADELEG = (Slot, (VKeyGenesis, VKey))
   type Environment ADELEG = Set VKeyGenesis
   type PredicateFailure ADELEG = AdelegPredicateFailure
-  data Event _
 
 
   initialRules = [
@@ -435,7 +433,6 @@ instance STS SDELEGS where
   type Signal SDELEGS = [DCert]
   type Environment SDELEGS = DSEnv
   type PredicateFailure SDELEGS = SdelegsPredicateFailure
-  data Event _ = SDelegEvent (Event SDELEG)
 
   initialRules = [ do
                      IRC env <- judgmentContext
@@ -454,7 +451,6 @@ instance STS SDELEGS where
 
 instance Embed SDELEG SDELEGS where
   wrapFailed = SDelegFailure
-  wrapEvent = SDelegEvent
 
 -- | Delegation rules sequencing
 data ADELEGS deriving (Data, Typeable)
@@ -467,7 +463,6 @@ instance STS ADELEGS where
   type State ADELEGS = DState
   type Signal ADELEGS = [(Slot, (VKeyGenesis, VKey))]
   type Environment ADELEGS = Set VKeyGenesis
-  data Event _ = ADelegEvent (Event ADELEG)
 
   type PredicateFailure ADELEGS
     = AdelegsPredicateFailure
@@ -489,7 +484,6 @@ instance STS ADELEGS where
 
 instance Embed ADELEG ADELEGS where
   wrapFailed = ADelegFailure
-  wrapEvent = ADelegEvent
 
 -- | Delegation interface
 data DELEG deriving (Data, Typeable)
@@ -505,9 +499,6 @@ instance STS DELEG where
   type Environment DELEG = DIEnv
 
   type PredicateFailure DELEG = DelegPredicateFailure
-  data Event _
-    = SDelegSEvent (Event SDELEGS)
-    | ADelegSEvent (Event ADELEGS)
 
   initialRules = [ do
                      IRC env <- judgmentContext
@@ -537,11 +528,9 @@ instance STS DELEG where
 
 instance Embed SDELEGS DELEG where
   wrapFailed = SDelegSFailure
-  wrapEvent = SDelegSEvent
 
 instance Embed ADELEGS DELEG where
   wrapFailed = ADelegSFailure
-  wrapEvent = ADelegSEvent
 
 --------------------------------------------------------------------------------
 -- Generators
@@ -621,7 +610,6 @@ instance STS MSDELEG where
   type State MSDELEG = DSState
   type Signal MSDELEG = Maybe DCert
   type PredicateFailure MSDELEG = MsdelegPredicateFailure
-  data Event _ = SDELEGEvent (Event SDELEG)
 
   initialRules = []
 
@@ -635,7 +623,6 @@ instance STS MSDELEG where
 
 instance Embed SDELEG MSDELEG where
   wrapFailed = SDELEGFailure
-  wrapEvent = SDELEGEvent
 
 instance HasTrace MSDELEG where
 
diff --git a/byron/ledger/executable-spec/src/Byron/Spec/Ledger/STS/UTXO.hs b/byron/ledger/executable-spec/src/Byron/Spec/Ledger/STS/UTXO.hs
index fdab458960..d626f5b01d 100644
--- a/byron/ledger/executable-spec/src/Byron/Spec/Ledger/STS/UTXO.hs
+++ b/byron/ledger/executable-spec/src/Byron/Spec/Ledger/STS/UTXO.hs
@@ -27,7 +27,7 @@ import           Data.Data (Data, Typeable)
 import qualified Data.Set as Set
 import           GHC.Generics (Generic)
 
-import           Control.State.Transition (Environment, IRC (IRC), PredicateFailure, STS, Event, Signal,
+import           Control.State.Transition (Environment, IRC (IRC), PredicateFailure, STS, Signal,
                      State, TRC (TRC), initialRules, judgmentContext, transitionRules, (?!))
 import           Byron.Spec.Ledger.Core (Lovelace, dom, range, (∪), (⊆), (⋪), (◁))
 import           Byron.Spec.Ledger.GlobalParams (lovelaceCap)
@@ -70,7 +70,6 @@ instance STS UTXO where
   type State UTXO = UTxOState
   type Signal UTXO = Tx
   type PredicateFailure UTXO = UtxoPredicateFailure
-  data Event _
 
   initialRules =
     [ do
diff --git a/byron/ledger/executable-spec/src/Byron/Spec/Ledger/STS/UTXOW.hs b/byron/ledger/executable-spec/src/Byron/Spec/Ledger/STS/UTXOW.hs
index a2418e52d6..439081c645 100644
--- a/byron/ledger/executable-spec/src/Byron/Spec/Ledger/STS/UTXOW.hs
+++ b/byron/ledger/executable-spec/src/Byron/Spec/Ledger/STS/UTXOW.hs
@@ -25,7 +25,7 @@ import qualified Hedgehog.Gen as Gen
 import           Hedgehog.Internal.Property (CoverPercentage)
 import qualified Hedgehog.Range as Range
 
-import           Control.State.Transition (Embed(..), Environment, IRC (IRC), STS (..),
+import           Control.State.Transition (Embed, Environment, IRC (IRC), STS (..),
                      Signal, State, TRC (TRC), initialRules, judgmentContext, trans,
                      transitionRules, wrapFailed, (?!))
 import           Control.State.Transition.Generator (HasTrace, SignalGenerator, coverFailures,
@@ -58,7 +58,6 @@ instance STS UTXOW where
   type State UTXOW = UTxOState
   type Signal UTXOW = Tx
   type PredicateFailure UTXOW = UtxowPredicateFailure
-  data Event _ = UtxoEvent (Event UTXO)
 
   initialRules =
     [ do
@@ -94,7 +93,6 @@ witnessed (Tx tx wits) utxo =
 
 instance Embed UTXO UTXOW where
   wrapFailed = UtxoFailure
-  wrapEvent = UtxoEvent
 
 -- | Constant list of addresses intended to be used in the generators.
 traceAddrs :: [Addr]
diff --git a/byron/ledger/executable-spec/src/Byron/Spec/Ledger/STS/UTXOWS.hs b/byron/ledger/executable-spec/src/Byron/Spec/Ledger/STS/UTXOWS.hs
index c14c5ba4fa..c87834773b 100644
--- a/byron/ledger/executable-spec/src/Byron/Spec/Ledger/STS/UTXOWS.hs
+++ b/byron/ledger/executable-spec/src/Byron/Spec/Ledger/STS/UTXOWS.hs
@@ -20,9 +20,9 @@ import           GHC.Generics (Generic)
 import           Byron.Spec.Ledger.STS.UTXO (UTxOEnv, UTxOState)
 import           Byron.Spec.Ledger.STS.UTXOW (UTXOW)
 import           Byron.Spec.Ledger.UTxO (Tx)
-import           Control.State.Transition (Embed, Environment, IRC (IRC), PredicateFailure, STS(..),
+import           Control.State.Transition (Embed, Environment, IRC (IRC), PredicateFailure, STS,
                      Signal, State, TRC (TRC), initialRules, judgmentContext, trans,
-                     transitionRules, wrapFailed, wrapEvent)
+                     transitionRules, wrapFailed)
 import           Control.State.Transition.Generator (HasTrace, envGen, genTrace, sigGen)
 import           Control.State.Transition.Trace (TraceOrder (OldestFirst), traceSignals)
 
@@ -37,7 +37,6 @@ instance STS UTXOWS where
   type Signal UTXOWS = [Tx]
   type Environment UTXOWS = UTxOEnv
   type PredicateFailure UTXOWS = UtxowsPredicateFailure
-  data Event _ = UtxowEvent (Event UTXOW)
 
   initialRules =
     [ do
@@ -58,7 +57,6 @@ instance STS UTXOWS where
 
 instance Embed UTXOW UTXOWS where
   wrapFailed = UtxowFailure
-  wrapEvent = UtxowEvent
 
 instance HasTrace UTXOWS where
   envGen = envGen @UTXOW
diff --git a/byron/ledger/executable-spec/src/Byron/Spec/Ledger/Update.hs b/byron/ledger/executable-spec/src/Byron/Spec/Ledger/Update.hs
index d4c7fb36e4..1c22a5421a 100644
--- a/byron/ledger/executable-spec/src/Byron/Spec/Ledger/Update.hs
+++ b/byron/ledger/executable-spec/src/Byron/Spec/Ledger/Update.hs
@@ -385,7 +385,6 @@ instance STS UPSVV where
   type State UPSVV = Map UpId (ApName, ApVer, Metadata)
   type Signal UPSVV = UProp
   type PredicateFailure UPSVV = UpsvvPredicateFailure
-  data Event _
 
   initialRules = []
   transitionRules =
@@ -424,7 +423,6 @@ instance STS UPPVV where
   type State UPPVV = Map UpId (ProtVer, PParams)
   type Signal UPPVV = UProp
   type PredicateFailure UPPVV = UppvvPredicateFailure
-  data Event _
 
   initialRules = []
   transitionRules =
@@ -467,9 +465,6 @@ instance STS UPV where
   type Signal UPV = UProp
   type PredicateFailure UPV = UpvPredicateFailure
 
-  data Event _
-    = UPPVVEvent (Event UPPVV)
-    | UPSVVEvent (Event UPSVV)
 
   initialRules = []
   transitionRules =
@@ -505,11 +500,9 @@ instance STS UPV where
 
 instance Embed UPPVV UPV where
   wrapFailed = UPPVVFailure
-  wrapEvent = UPPVVEvent
 
 instance Embed UPSVV UPV where
   wrapFailed = UPSVVFailure
-  wrapEvent = UPSVVEvent
 
 data UPREG deriving (Generic, Data, Typeable)
 -- | These `PredicateFailure`s are all throwable.
@@ -532,8 +525,6 @@ instance STS UPREG where
     )
   type Signal UPREG = UProp
   type PredicateFailure UPREG = UpregPredicateFailure
-  data Event _
-    = UPVEvent (Event UPV)
 
   initialRules = []
   transitionRules =
@@ -553,7 +544,6 @@ instance STS UPREG where
 
 instance Embed UPV UPREG where
   wrapFailed = UPVFailure
-  wrapEvent = UPVEvent
 
 ------------------------------------------------------------------------
 -- Update voting
@@ -602,7 +592,6 @@ instance STS ADDVOTE where
   type State ADDVOTE = Set (UpId, Core.VKeyGenesis)
   type Signal ADDVOTE = Vote
   type PredicateFailure ADDVOTE = AddvotePredicateFailure
-  data Event _
 
   initialRules = []
   transitionRules =
@@ -649,7 +638,6 @@ instance STS UPVOTE where
     )
   type Signal UPVOTE = Vote
   type PredicateFailure UPVOTE = UpvotePredicateFailure
-  data Event _ = ADDVOTEEvent (Event ADDVOTE)
 
   initialRules = []
   transitionRules =
@@ -681,7 +669,6 @@ instance STS UPVOTE where
 
 instance Embed ADDVOTE UPVOTE where
   wrapFailed = ADDVOTEFailure
-  wrapEvent = ADDVOTEEvent
 
 ------------------------------------------------------------------------
 -- Update voting
@@ -697,7 +684,6 @@ instance STS FADS where
   type State FADS = [(Core.Slot, (ProtVer, PParams))]
   type Signal FADS = (Core.Slot, (ProtVer, PParams))
   type PredicateFailure FADS = FadsPredicateFailure
-  data Event _
 
   initialRules = []
   transitionRules =
@@ -753,7 +739,6 @@ instance STS UPEND where
     )
   type Signal UPEND = (ProtVer, Core.VKey)
   type PredicateFailure UPEND = UpendPredicateFailure
-  data Event _ = FADSEvent (Event FADS)
 
   initialRules = []
   transitionRules =
@@ -825,7 +810,6 @@ instance STS UPEND where
 
 instance Embed FADS UPEND where
   wrapFailed = error "No possible failures in FADS"
-  wrapEvent = FADSEvent
 
 ------------------------------------------------------------------------
 -- Update interface
@@ -964,7 +948,6 @@ instance STS UPIREG where
   type State UPIREG = UPIState
   type Signal UPIREG = UProp
   type PredicateFailure UPIREG = UpiregPredicateFailure
-  data Event _ = UPREGEvent (Event UPREG)
 
   initialRules = [ return $! emptyUPIState ]
 
@@ -998,7 +981,6 @@ instance STS UPIREG where
 
 instance Embed UPREG UPIREG where
   wrapFailed = UPREGFailure
-  wrapEvent = UPREGEvent
 
 instance HasTrace UPIREG where
 
@@ -1342,7 +1324,6 @@ instance STS UPIVOTE where
   type State UPIVOTE = UPIState
   type Signal UPIVOTE = Vote
   type PredicateFailure UPIVOTE = UpivotePredicateFailure
-  data Event _ = UPVOTEEvent (Event UPVOTE)
 
   initialRules = []
   transitionRules =
@@ -1383,7 +1364,6 @@ instance STS UPIVOTE where
 
 instance Embed UPVOTE UPIVOTE where
   wrapFailed = UPVOTEFailure
-  wrapEvent = UPVOTEEvent
 
 
 data APPLYVOTES deriving (Generic, Data, Typeable)
@@ -1397,7 +1377,6 @@ instance STS APPLYVOTES where
   type State APPLYVOTES = UPIState
   type Signal APPLYVOTES = [Vote]
   type PredicateFailure APPLYVOTES = ApplyVotesPredicateFailure
-  data Event _ = UpivoteEvent (Event UPIVOTE)
 
   initialRules = [ return $! emptyUPIState ]
 
@@ -1414,7 +1393,6 @@ instance STS APPLYVOTES where
 
 instance Embed UPIVOTE APPLYVOTES where
   wrapFailed = UpivoteFailure
-  wrapEvent = UpivoteEvent
 
 data UPIVOTES deriving (Generic, Data, Typeable)
 
@@ -1427,7 +1405,6 @@ instance STS UPIVOTES where
   type State UPIVOTES = UPIState
   type Signal UPIVOTES = [Vote]
   type PredicateFailure UPIVOTES = UpivotesPredicateFailure
-  data Event _ = ApplyVotesEvent (Event APPLYVOTES)
 
   initialRules = [ return $! emptyUPIState ]
 
@@ -1474,7 +1451,6 @@ instance STS UPIVOTES where
 
 instance Embed APPLYVOTES UPIVOTES where
   wrapFailed = ApplyVotesFailure
-  wrapEvent = ApplyVotesEvent
 
 instance HasTrace UPIVOTES where
 
@@ -1575,7 +1551,6 @@ instance STS UPIEND where
   type State UPIEND = UPIState
   type Signal UPIEND = (ProtVer, Core.VKey)
   type PredicateFailure UPIEND = UpiendPredicateFailure
-  data Event _ = UPENDEvent (Event UPEND)
 
   initialRules = [ return $! emptyUPIState ]
 
@@ -1615,7 +1590,6 @@ instance STS UPIEND where
 
 instance Embed UPEND UPIEND where
   wrapFailed = UPENDFailure
-  wrapEvent = UPENDEvent
 
 -- | Given a list of protocol versions and keys endorsing those versions,
 -- generate a protocol-version endorsement, or 'Nothing' if the list of
@@ -1658,8 +1632,6 @@ instance STS PVBUMP where
   type Signal PVBUMP = ()
   type PredicateFailure PVBUMP = PvbumpPredicateFailure
 
-  data Event _
-
   initialRules = []
   transitionRules =
     [ do
@@ -1688,7 +1660,6 @@ instance STS UPIEC where
   type State UPIEC = UPIState
   type Signal UPIEC = ()
   type PredicateFailure UPIEC = UpiecPredicateFailure
-  data Event _ = PVBUMPEvent (Event PVBUMP)
 
   initialRules = []
   transitionRules =
@@ -1720,7 +1691,6 @@ instance STS UPIEC where
 
 instance Embed PVBUMP UPIEC where
   wrapFailed = PVBUMPFailure
-  wrapEvent = PVBUMPEvent
 
 -- | Generate an optional update-proposal and a list of votes, given an update
 -- environment and state.
diff --git a/byron/ledger/executable-spec/test/Test/Byron/Spec/Ledger/Delegation/Properties.hs b/byron/ledger/executable-spec/test/Test/Byron/Spec/Ledger/Delegation/Properties.hs
index 1ec3ba05d9..15006d6078 100644
--- a/byron/ledger/executable-spec/test/Test/Byron/Spec/Ledger/Delegation/Properties.hs
+++ b/byron/ledger/executable-spec/test/Test/Byron/Spec/Ledger/Delegation/Properties.hs
@@ -40,8 +40,8 @@ import           Lens.Micro.Extras (view)
 import           Lens.Micro.TH (makeLenses)
 
 import           Control.State.Transition (Embed, Environment, IRC (IRC), PredicateFailure, STS,
-                     Signal, State, TRC (TRC), Event, applySTS, initialRules, judgmentContext, trans,
-                     transitionRules, wrapFailed, (?!), wrapEvent)
+                     Signal, State, TRC (TRC), applySTS, initialRules, judgmentContext, trans,
+                     transitionRules, wrapFailed, (?!))
 import           Control.State.Transition.Generator (HasSizeInfo, HasTrace, SignalGenerator,
                      TraceProfile (TraceProfile), classifySize, classifyTraceLength, envGen,
                      failures, isTrivial, nonTrivialTrace, proportionOfValidSignals, sigGen,
@@ -109,8 +109,6 @@ instance STS DBLOCK where
   type State DBLOCK = (DSEnv, DIState)
   type Signal DBLOCK = DBlock
   type PredicateFailure DBLOCK = DBlockPredicateFailure
-  data Event _ =
-    DELEGEvent (Event DELEG)
 
   initialRules
     = [ do
@@ -134,7 +132,6 @@ instance STS DBLOCK where
 
 instance Embed DELEG DBLOCK where
   wrapFailed = DPF
-  wrapEvent = DELEGEvent
 
 -- | Check that all the delegation certificates in the trace were correctly
 -- applied.
diff --git a/byron/ledger/executable-spec/test/Test/Byron/Spec/Ledger/Update/Properties.hs b/byron/ledger/executable-spec/test/Test/Byron/Spec/Ledger/Update/Properties.hs
index 41b53fd68e..95543ed074 100644
--- a/byron/ledger/executable-spec/test/Test/Byron/Spec/Ledger/Update/Properties.hs
+++ b/byron/ledger/executable-spec/test/Test/Byron/Spec/Ledger/Update/Properties.hs
@@ -34,9 +34,9 @@ import qualified Hedgehog.Gen as Gen
 import qualified Hedgehog.Range as Range
 import           Numeric.Natural (Natural)
 
-import           Control.State.Transition (Embed, Environment, IRC (IRC), PredicateFailure, STS, Event,
+import           Control.State.Transition (Embed, Environment, IRC (IRC), PredicateFailure, STS,
                      Signal, State, TRC (TRC), initialRules, judgmentContext, trans,
-                     transitionRules, wrapFailed, (?!), wrapEvent)
+                     transitionRules, wrapFailed, (?!))
 import           Control.State.Transition.Generator (HasTrace, SignalGenerator, envGen,
                      randomTraceOfSize, ratio, sigGen, trace, traceLengthsAreClassified,
                      traceOfLength)
@@ -305,11 +305,6 @@ instance STS UBLOCK where
 
   type PredicateFailure UBLOCK = UBlockPredicateFailure
 
-  data Event _
-    = UPIREGEvent (Event UPIREG)
-    | UPIVOTESEvent (Event UPIVOTES)
-    | UPIENDEvent (Event UPIEND)
-
   initialRules
     = [ do
           IRC env <- judgmentContext
@@ -356,15 +351,12 @@ instance STS UBLOCK where
 
 instance Embed UPIREG UBLOCK where
   wrapFailed = UPIREGFailure
-  wrapEvent = UPIREGEvent
 
 instance Embed UPIVOTES UBLOCK where
   wrapFailed = UPIVOTESFailure
-  wrapEvent = UPIVOTESEvent
 
 instance Embed UPIEND UBLOCK where
   wrapFailed = UPIENDFailure
-  wrapEvent = UPIENDEvent
 
 instance HasTrace UBLOCK where
   envGen _ =
diff --git a/byron/ledger/impl/test/Test/Cardano/Chain/Update/Gen.hs b/byron/ledger/impl/test/Test/Cardano/Chain/Update/Gen.hs
index 456cdb37d0..fea96c4afb 100644
--- a/byron/ledger/impl/test/Test/Cardano/Chain/Update/Gen.hs
+++ b/byron/ledger/impl/test/Test/Cardano/Chain/Update/Gen.hs
@@ -250,6 +250,6 @@ genEndorsementError = Endorsement.MultipleProposalsForProtocolVersion <$>
   genProtocolVersion
 
 genRegistrationTooLarge :: Gen (Registration.TooLarge Int)
-genRegistrationTooLarge = Registration.TooLarge
+genRegistrationTooLarge = Registration.TooLarge 
   <$> Gen.int Range.constantBounded
   <*> Gen.int Range.constantBounded
diff --git a/cardano-ledger-core/src/Cardano/Ledger/Rules/ValidationMode.hs b/cardano-ledger-core/src/Cardano/Ledger/Rules/ValidationMode.hs
index cba9cbcf9c..5652542a87 100644
--- a/cardano-ledger-core/src/Cardano/Ledger/Rules/ValidationMode.hs
+++ b/cardano-ledger-core/src/Cardano/Ledger/Rules/ValidationMode.hs
@@ -29,7 +29,7 @@ applySTSValidateSuchThat ::
   RuleContext rtype s ->
   m (Either [[PredicateFailure s]] (State s))
 applySTSValidateSuchThat cond ctx =
-  applySTSOpts EPDiscard opts ctx <&> \case
+  applySTSOpts opts ctx <&> \case
     (st, []) -> Right st
     (_, pfs) -> Left pfs
   where
diff --git a/semantics/executable-spec/small-steps.cabal b/semantics/executable-spec/small-steps.cabal
index a26dac2e16..585e7e125a 100644
--- a/semantics/executable-spec/small-steps.cabal
+++ b/semantics/executable-spec/small-steps.cabal
@@ -69,7 +69,6 @@ library
                      , strict-containers
                      , text
                      , transformers >= 0.5
-                     , writer-cps-mtl
                      -- IOHK deps
                      , cardano-crypto-class
                      , cardano-binary
diff --git a/semantics/executable-spec/src/Control/State/Transition/Extended.hs b/semantics/executable-spec/src/Control/State/Transition/Extended.hs
index 10c486f0a0..9f072b0dd4 100644
--- a/semantics/executable-spec/src/Control/State/Transition/Extended.hs
+++ b/semantics/executable-spec/src/Control/State/Transition/Extended.hs
@@ -38,18 +38,12 @@ module Control.State.Transition.Extended
     (?!),
     (?!:),
     Label,
-    SingEP(..),
-    EventPolicy(..),
-    EventReturnType,
-    EventConstraintType,
     labeledPred,
     labeledPredE,
     failBecause,
     judgmentContext,
     trans,
     liftSTS,
-    tellEvent,
-    tellEvents,
 
     -- * Apply STS
     AssertionPolicy (..),
@@ -77,16 +71,14 @@ import Control.Monad (when)
 import Control.Monad.Except (MonadError (..))
 import Control.Monad.Free.Church
 import Control.Monad.Identity (Identity (..))
-import Control.Monad.Trans.Class (lift, MonadTrans)
-import Control.Monad.Trans.State.Strict (StateT(..))
-import Control.Monad.Writer.CPS (WriterT, runWriterT)
-import Control.Monad.Writer.Class (MonadWriter (..))
-import Control.Monad.State.Class (MonadState (..), modify)
+import Control.Monad.Trans.Class (lift)
+import Control.Monad.Trans.State.Strict (modify, runStateT)
+import qualified Control.Monad.Trans.State.Strict as MonadState
 import Data.Data (Data, Typeable)
 import Data.Default.Class (Default, def)
 import Data.Foldable (find, traverse_)
-import Data.Functor ((<&>), ($>))
-import Data.Kind (Type, Constraint)
+import Data.Functor ((<&>))
+import Data.Kind (Type)
 import Data.Proxy (Proxy (..))
 import Data.Typeable (typeRep)
 import NoThunks.Class (NoThunks (..))
@@ -186,12 +178,6 @@ class
 
   type BaseM a = Identity
 
-  -- | Event type.
-  data Event a :: Type
-
-  -- type Event a :: Type
-  -- type Event a = Void
-
   -- | Descriptive type for the possible failures which might cause a transition
   -- to fail.
   --
@@ -229,37 +215,9 @@ class
 class (STS sub, BaseM sub ~ BaseM super) => Embed sub super where
   -- | Wrap a predicate failure of the subsystem in a failure of the super-system.
   wrapFailed :: PredicateFailure sub -> PredicateFailure super
-  wrapEvent :: Event sub -> Event super
 
 instance STS sts => Embed sts sts where
   wrapFailed = id
-  wrapEvent = id
-
-data EventPolicy
-  = EventPolicyReturn
-  | EventPolicyDiscard
-
-data SingEP ep where
-  EPReturn  :: SingEP 'EventPolicyReturn
-  EPDiscard :: SingEP 'EventPolicyDiscard
-
-type family EventReturnType ep sts a :: Type where
-  EventReturnType 'EventPolicyReturn sts a = (a, [Event sts])
-  EventReturnType _ _ a = a
-
-type family EventConstraintType e sts m :: Constraint where
-  EventConstraintType 'EventPolicyReturn sts m = MonadWriter [Event sts] m
-  EventConstraintType _ _ _ = ()
-
-discardEvents :: forall ep a. SingEP ep -> forall s. EventReturnType ep s a -> a
-discardEvents ep = case ep of
-  EPReturn -> fst
-  EPDiscard -> id
-
-getEvents :: forall ep. SingEP ep -> forall s a. EventReturnType ep s a -> [Event s]
-getEvents ep ert = case ep of
-  EPReturn -> snd ert
-  EPDiscard -> []
 
 data Clause sts (rtype :: RuleType) a where
   Lift ::
@@ -276,10 +234,6 @@ data Clause sts (rtype :: RuleType) a where
     -- Subsequent computation with state introduced
     (State sub -> a) ->
     Clause sts rtype a
-  Writer ::
-    [Event sts] ->
-    a ->
-    Clause sts rtype a
   Predicate ::
     [Label] ->
     Either e a ->
@@ -376,33 +330,32 @@ data ApplySTSOpts = ApplySTSOpts
     asoValidation :: ValidationPolicy
   }
 
-type STSInterpreter ep =
+type STSInterpreter =
   forall s m rtype.
   (STS s, RuleTypeRep rtype, m ~ BaseM s) =>
   RuleContext rtype s ->
-  m (EventReturnType ep s (State s, [[PredicateFailure s]]))
+  m (State s, [[PredicateFailure s]])
 
-type RuleInterpreter ep =
+type RuleInterpreter =
   forall s m rtype.
   (STS s, RuleTypeRep rtype, m ~ BaseM s) =>
   RuleContext rtype s ->
   Rule s rtype (State s) ->
-  m (EventReturnType ep s (State s, [PredicateFailure s]))
+  m (State s, [PredicateFailure s])
 
 -- | Apply an STS with options. Note that this returns both the final state and
 -- the list of predicate failures.
 applySTSOpts ::
-  forall s m rtype ep.
+  forall s m rtype.
   (STS s, RuleTypeRep rtype, m ~ BaseM s) =>
-  SingEP ep ->
   ApplySTSOpts ->
   RuleContext rtype s ->
-  m (EventReturnType ep s (State s, [[PredicateFailure s]]))
-applySTSOpts ep ApplySTSOpts {asoAssertions, asoValidation} ctx =
-  let goRule :: RuleInterpreter ep
-      goRule = applyRuleInternal ep asoValidation goSTS
-      goSTS :: STSInterpreter ep
-      goSTS = applySTSInternal ep asoAssertions goRule
+  m (State s, [[PredicateFailure s]])
+applySTSOpts ApplySTSOpts {asoAssertions, asoValidation} ctx =
+  let goRule :: RuleInterpreter
+      goRule = applyRuleInternal asoValidation goSTS
+      goSTS :: STSInterpreter
+      goSTS = applySTSInternal asoAssertions goRule
    in goSTS ctx
 
 applySTS ::
@@ -411,7 +364,7 @@ applySTS ::
   RuleContext rtype s ->
   m (Either [[PredicateFailure s]] (State s))
 applySTS ctx =
-  applySTSOpts EPDiscard defaultOpts ctx <&> \case
+  applySTSOpts defaultOpts ctx <&> \case
     (st, []) -> Right st
     (_, pfs) -> Left pfs
   where
@@ -441,7 +394,7 @@ reapplySTS ::
   RuleContext rtype s ->
   m (State s)
 reapplySTS ctx =
-  applySTSOpts EPDiscard defaultOpts ctx <&> fst
+  applySTSOpts defaultOpts ctx <&> fst
   where
     defaultOpts =
       ApplySTSOpts
@@ -455,7 +408,7 @@ applySTSIndifferently ::
   RuleContext rtype s ->
   m (State s, [[PredicateFailure s]])
 applySTSIndifferently =
-  applySTSOpts EPDiscard opts
+  applySTSOpts opts
   where
     opts =
       ApplySTSOpts
@@ -463,44 +416,22 @@ applySTSIndifferently =
           asoValidation = ValidateAll
         }
 
-newtype RuleEventLoggerT s m a = RuleEventLoggerT (StateT [PredicateFailure s] (WriterT [Event s] m) a)
-  deriving (MonadWriter [Event s], Monad, Applicative, Functor)
-
-deriving instance (x ~ [PredicateFailure s], Monad m) => MonadState x (RuleEventLoggerT s m)
-
-instance MonadTrans (RuleEventLoggerT s) where
-  lift = RuleEventLoggerT . lift . lift
-
-runRuleEventLoggerT :: forall s m a. RuleEventLoggerT s m a -> [PredicateFailure s] -> m ((a, [PredicateFailure s]), [Event s])
-runRuleEventLoggerT (RuleEventLoggerT m) s = runWriterT $ runStateT m s
-
 -- | Apply a rule even if its predicates fail.
 --
 --   If the rule successfully applied, the list of predicate failures will be
 --   empty.
 applyRuleInternal ::
-  forall (ep :: EventPolicy) s m rtype.
+  forall s m rtype.
   (STS s, RuleTypeRep rtype, m ~ BaseM s) =>
-  SingEP ep ->
   ValidationPolicy ->
   -- | Interpreter for subsystems
-  STSInterpreter ep ->
+  STSInterpreter ->
   RuleContext rtype s ->
   Rule s rtype (State s) ->
-  m (EventReturnType ep s (State s, [PredicateFailure s]))
-applyRuleInternal ep vp goSTS jc r =
-  case ep of
-    EPReturn -> flip (runRuleEventLoggerT @s) [] $ foldF runClause r
-    EPDiscard -> flip runStateT [] $ foldF runClause r
+  m (State s, [PredicateFailure s])
+applyRuleInternal vp goSTS jc r = flip runStateT [] $ foldF runClause r
   where
-    runClause :: forall f t a.
-      ( f ~ t m
-      , MonadState [PredicateFailure s] f
-      , EventConstraintType ep s f
-      , MonadTrans t
-      )
-      => Clause s rtype a
-      -> t m a
+    runClause :: Clause s rtype a -> MonadState.StateT [PredicateFailure s] m a
     runClause (Lift f next) = next <$> lift f
     runClause (GetCtx next) = pure $ next jc
     runClause (Predicate lbls cond orElse val) =
@@ -511,52 +442,38 @@ applyRuleInternal ep vp goSTS jc r =
             Right x -> pure x
         else pure val
     runClause (SubTrans (subCtx :: RuleContext _rtype sub) next) = do
-      s <- lift $ goSTS subCtx
-      let ss :: State sub
-          sfails :: [[PredicateFailure sub]]
-          (ss, sfails) = (discardEvents ep @sub) s
+      (ss, sfails) <- lift $ goSTS subCtx
       traverse_ (\a -> modify (a :)) $ wrapFailed @sub @s <$> concat sfails
-      runClause $ Writer (fmap wrapEvent $ getEvents ep @sub @(State sub, [[PredicateFailure sub]]) s) ()
       pure $ next ss
-    runClause (Writer w a) = case ep of
-      EPReturn -> tell w $> a
-      EPDiscard -> pure a
+
     validateIf lbls = case vp of
       ValidateAll -> True
       ValidateNone -> False
       ValidateSuchThat f -> f lbls
 
 applySTSInternal ::
-  forall s m rtype ep.
+  forall s m rtype.
   (STS s, RuleTypeRep rtype, m ~ BaseM s) =>
-  SingEP ep ->
   AssertionPolicy ->
   -- | Interpreter for rules
-  RuleInterpreter ep ->
+  RuleInterpreter ->
   RuleContext rtype s ->
-  m (EventReturnType ep s (State s, [[PredicateFailure s]]))
-applySTSInternal ep ap goRule ctx =
+  m (State s, [[PredicateFailure s]])
+applySTSInternal ap goRule ctx =
   successOrFirstFailure <$> applySTSInternal' rTypeRep ctx
   where
-    successOrFirstFailure ::
-         [EventReturnType ep s (State s, [PredicateFailure s])]
-      -> EventReturnType ep s (State s, [[PredicateFailure s]])
     successOrFirstFailure xs =
-      case find (\x -> null $ snd $ (discardEvents ep @s x :: (State s, [PredicateFailure s]))) xs of
+      case find (null . snd) xs of
         Nothing ->
           case xs of
             [] -> error "applySTSInternal was called with an empty set of rules"
-            s' : _ -> case ep of
-              EPDiscard -> (fst s', snd <$> xs)
-              EPReturn -> ((fst $ fst s', (snd . fst) <$> xs), snd s')
-        Just s' -> case ep of
-          EPDiscard -> (fst s', [])
-          EPReturn -> ((fst $ fst s', []), snd s')
+            (s, _) : _ -> (s, snd <$> xs)
+        Just (s, _) -> (s, [])
 
     applySTSInternal' ::
       SRuleType rtype ->
       RuleContext rtype s ->
-      m [EventReturnType ep s (State s, [PredicateFailure s])]
+      m [(State s, [PredicateFailure s])]
     applySTSInternal' SInitial env =
       goRule env `traverse` initialRules
     applySTSInternal' STransition jc = do
@@ -581,7 +498,7 @@ applySTSInternal ep ap goRule ctx =
       res <- goRule jc `traverse` transitionRules
       -- We only care about running postconditions if the state transition was
       -- successful.
-      !_ <- case (assertPost ap, discardEvents ep @s (successOrFirstFailure res) :: (State s, [[PredicateFailure s]])) of
+      !_ <- case (assertPost ap, successOrFirstFailure res) of
         (True, (st, [])) ->
           sfor_ (assertions @s)
             $! ( \case
@@ -642,7 +559,6 @@ instance
   type Signal (STUB e st si f m) = si
   type PredicateFailure (STUB e st si f m) = f
   type BaseM (STUB e st si f m) = m
-  data Event _
 
   transitionRules = []
   initialRules = []
@@ -672,13 +588,3 @@ straverse_ f = foldr c (pure ())
 sfor_ :: (Foldable t, Applicative f) => t a -> (a -> f b) -> f ()
 {-# INLINE sfor_ #-}
 sfor_ = flip straverse_
-
-tellEvent ::
-  Event sts ->
-  Rule sts ctx ()
-tellEvent e = tellEvents [e]
-
-tellEvents ::
-  [Event sts] ->
-  Rule sts ctx ()
-tellEvents es = liftF $ Writer es ()
diff --git a/semantics/small-steps-test/src/Control/State/Transition/Trace.hs b/semantics/small-steps-test/src/Control/State/Transition/Trace.hs
index 108b010d4b..41372eeb19 100644
--- a/semantics/small-steps-test/src/Control/State/Transition/Trace.hs
+++ b/semantics/small-steps-test/src/Control/State/Transition/Trace.hs
@@ -132,7 +132,6 @@ mkTrace env initState sigs = Trace env initState sigs'
 --   type State DUMMY = Int
 --   type Signal DUMMY = String
 --   type PredicateFailure DUMMY = DummyPredicateFailure
---   data Event _
 --   initialRules = []
 --   transitionRules = []
 -- :}
@@ -355,7 +354,6 @@ preStatesAndSignals NewestFirst tr
 --   type State ADDER = Int
 --   type Signal ADDER = Int
 --   type PredicateFailure ADDER = AdderPredicateFailure
---   data Event _
 --   initialRules = [ pure 0 ]
 --   transitionRules =
 --     [ do
@@ -497,7 +495,7 @@ applySTSTest ::
   RuleContext rtype s ->
   m (Either [[PredicateFailure s]] (State s))
 applySTSTest ctx =
-  applySTSOpts EPDiscard defaultOpts ctx <&> \case
+  applySTSOpts defaultOpts ctx <&> \case
     (st, []) -> Right st
     (_, pfs) -> Left pfs
   where
diff --git a/semantics/small-steps-test/test/Control/State/Transition/Examples/CommitReveal.hs b/semantics/small-steps-test/test/Control/State/Transition/Examples/CommitReveal.hs
index 9c06ead4ef..d9f282422a 100644
--- a/semantics/small-steps-test/test/Control/State/Transition/Examples/CommitReveal.hs
+++ b/semantics/small-steps-test/test/Control/State/Transition/Examples/CommitReveal.hs
@@ -22,7 +22,6 @@ import Control.State.Transition
     STS,
     Signal,
     State,
-    Event,
     TRC (TRC),
     initialRules,
     judgmentContext,
@@ -138,8 +137,6 @@ instance
     PredicateFailure (CR hashAlgo hashToDataMap commitData) =
       CRPredicateFailure hashAlgo hashToDataMap commitData
 
-  data Event _ = Cert
-
   initialRules =
     [ pure
         $! CRSt
diff --git a/semantics/small-steps-test/test/Control/State/Transition/Examples/GlobalSum.hs b/semantics/small-steps-test/test/Control/State/Transition/Examples/GlobalSum.hs
index ee190bda4e..8f3615ba9c 100644
--- a/semantics/small-steps-test/test/Control/State/Transition/Examples/GlobalSum.hs
+++ b/semantics/small-steps-test/test/Control/State/Transition/Examples/GlobalSum.hs
@@ -33,8 +33,6 @@ instance STS GSUM where
 
   type PredicateFailure GSUM = NoFailure
 
-  data Event _
-
   initialRules = [pure 0]
 
   transitionRules =
diff --git a/semantics/small-steps-test/test/Control/State/Transition/Examples/Sum.hs b/semantics/small-steps-test/test/Control/State/Transition/Examples/Sum.hs
index f19a1bb78b..2486f14013 100644
--- a/semantics/small-steps-test/test/Control/State/Transition/Examples/Sum.hs
+++ b/semantics/small-steps-test/test/Control/State/Transition/Examples/Sum.hs
@@ -34,8 +34,6 @@ instance STS SUM where
 
   type PredicateFailure SUM = NoFailure
 
-  data Event _
-
   initialRules = [pure 0]
 
   transitionRules =
diff --git a/shelley-ma/impl/src/Cardano/Ledger/ShelleyMA/Rules/Utxo.hs b/shelley-ma/impl/src/Cardano/Ledger/ShelleyMA/Rules/Utxo.hs
index 34caae1cd3..439b239903 100644
--- a/shelley-ma/impl/src/Cardano/Ledger/ShelleyMA/Rules/Utxo.hs
+++ b/shelley-ma/impl/src/Cardano/Ledger/ShelleyMA/Rules/Utxo.hs
@@ -378,7 +378,6 @@ instance
   type
     PredicateFailure (UTXO era) =
       UtxoPredicateFailure era
-  data Event _ = UpdateEvent (Event (PPUP era))
 
   initialRules = []
   transitionRules = [utxoTransition]
@@ -391,7 +390,6 @@ instance
   Embed (PPUP era) (UTXO era)
   where
   wrapFailed = UpdateFailure
-  wrapEvent = UpdateEvent
 
 --------------------------------------------------------------------------------
 -- Serialisation
diff --git a/shelley-ma/impl/src/Cardano/Ledger/ShelleyMA/Rules/Utxow.hs b/shelley-ma/impl/src/Cardano/Ledger/ShelleyMA/Rules/Utxow.hs
index 6245219b83..142f27dd59 100644
--- a/shelley-ma/impl/src/Cardano/Ledger/ShelleyMA/Rules/Utxow.hs
+++ b/shelley-ma/impl/src/Cardano/Ledger/ShelleyMA/Rules/Utxow.hs
@@ -66,8 +66,6 @@ instance
   type
     PredicateFailure (UTXOW era) =
       UtxowPredicateFailure era
-  data Event _ = UtxoEvent (Event (UTXO era))
-
   transitionRules = [shelleyStyleWitness witsVKeyNeeded id]
 
   -- The ShelleyMA Era uses the same PredicateFailure type
@@ -82,15 +80,12 @@ instance
   Embed (UTXO era) (UTXOW era)
   where
   wrapFailed = UtxoFailure
-  wrapEvent = UtxoEvent
 
 instance
   ( Era era,
     STS (UTXOW era),
-    PredicateFailure (Core.EraRule "UTXOW" era) ~ UtxowPredicateFailure era,
-    Event (Core.EraRule "UTXOW" era) ~ Event (UTXOW era)
+    PredicateFailure (Core.EraRule "UTXOW" era) ~ UtxowPredicateFailure era
   ) =>
   Embed (UTXOW era) (Shelley.LEDGER era)
   where
   wrapFailed = Shelley.UtxowFailure
-  wrapEvent = Shelley.UtxowEvent
diff --git a/shelley-ma/shelley-ma-test/src/Test/Cardano/Ledger/TranslationTools.hs b/shelley-ma/shelley-ma-test/src/Test/Cardano/Ledger/TranslationTools.hs
index b3c52e5479..b1829ade9a 100644
--- a/shelley-ma/shelley-ma-test/src/Test/Cardano/Ledger/TranslationTools.hs
+++ b/shelley-ma/shelley-ma-test/src/Test/Cardano/Ledger/TranslationTools.hs
@@ -79,7 +79,7 @@ decodeTestAnn _ x =
    let bytes = serialize x
        decoded = decodeAnnotator mempty fromCBOR bytes :: Either DecoderError b
     in case decoded of
-  Left e -> assertFailure $
+  Left e -> assertFailure $ 
        "\nerror: " <> show e
     <> "\nbytes: " <> show (B16.encode bytes) <> "\n"
   Right _ -> return ()
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Bbody.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Bbody.hs
index df0b3d2e2f..91289e937d 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Bbody.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Bbody.hs
@@ -137,8 +137,6 @@ instance
   type BaseM (BBODY era) = ShelleyBase
 
   type PredicateFailure (BBODY era) = BbodyPredicateFailure era
-  data Event _
-    = LedgersEvent (Event (Core.EraRule "LEDGERS" era)) -- Subtransition Failures
 
   initialRules = []
   transitionRules = [bbodyTransition]
@@ -205,4 +203,3 @@ instance
   Embed ledgers (BBODY era)
   where
   wrapFailed = LedgersFailure
-  wrapEvent = LedgersEvent
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Chain.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Chain.hs
index 8aff81e0e0..8155200205 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Chain.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Chain.hs
@@ -18,7 +18,6 @@ module Shelley.Spec.Ledger.STS.Chain
   ( CHAIN,
     ChainState (..),
     ChainPredicateFailure (..),
-    Event (..),
     PredicateFailure,
     AdaPots (..),
     initialShelleyState,
@@ -271,12 +270,6 @@ instance
 
   type PredicateFailure (CHAIN era) = ChainPredicateFailure era
 
-  data Event _
-    = BbodyEvent (Event (Core.EraRule "BBODY" era))
-    | TicknEvent (Event TICKN)
-    | TickEvent (Event (TICK era))
-    | PrtclEvent (Event (PRTCL (Crypto era)))
-
   initialRules = []
   transitionRules = [chainTransition]
 
@@ -419,13 +412,11 @@ instance
   ( Era era,
     Era era,
     STS (BBODY era),
-    PredicateFailure (Core.EraRule "BBODY" era) ~ BbodyPredicateFailure era,
-    Event (Core.EraRule "BBODY" era) ~ Event (BBODY era)
+    PredicateFailure (Core.EraRule "BBODY" era) ~ BbodyPredicateFailure era
   ) =>
   Embed (BBODY era) (CHAIN era)
   where
   wrapFailed = BbodyFailure
-  wrapEvent = BbodyEvent
 
 instance
   ( Era era,
@@ -435,7 +426,6 @@ instance
   Embed TICKN (CHAIN era)
   where
   wrapFailed = TicknFailure
-  wrapEvent = TicknEvent
 
 instance
   ( Era era,
@@ -446,7 +436,6 @@ instance
   Embed (TICK era) (CHAIN era)
   where
   wrapFailed = TickFailure
-  wrapEvent = TickEvent
 
 instance
   ( Era era,
@@ -457,7 +446,6 @@ instance
   Embed (PRTCL c) (CHAIN era)
   where
   wrapFailed = PrtclFailure
-  wrapEvent = PrtclEvent
 
 data AdaPots = AdaPots
   { treasuryAdaPot :: Coin,
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Deleg.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Deleg.hs
index f78e25aeb6..e5c65d4f88 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Deleg.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Deleg.hs
@@ -149,7 +149,6 @@ instance
   type Environment (DELEG era) = DelegEnv era
   type BaseM (DELEG era) = ShelleyBase
   type PredicateFailure (DELEG era) = DelegPredicateFailure era
-  data Event _
 
   transitionRules = [delegationTransition]
 
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Delegs.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Delegs.hs
index af98c1ea07..eb76bd6f4d 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Delegs.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Delegs.hs
@@ -136,7 +136,6 @@ instance
   type
     PredicateFailure (DELEGS era) =
       DelegsPredicateFailure era
-  data Event _ = DelplEvent (Event (DELPL era))
 
   transitionRules = [delegsTransition]
 
@@ -263,4 +262,3 @@ instance
   Embed (DELPL era) (DELEGS era)
   where
   wrapFailed = DelplFailure
-  wrapEvent = DelplEvent
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Delpl.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Delpl.hs
index bf8edb2370..9af49edc55 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Delpl.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Delpl.hs
@@ -106,9 +106,6 @@ instance
   type Environment (DELPL era) = DelplEnv era
   type BaseM (DELPL era) = ShelleyBase
   type PredicateFailure (DELPL era) = DelplPredicateFailure era
-  data Event (DELPL era)
-    = DelegEvent (Event (DELEG era))
-    | PoolEvent (Event (POOL era))
 
   transitionRules = [delplTransition]
 
@@ -200,7 +197,6 @@ instance
   Embed (POOL era) (DELPL era)
   where
   wrapFailed = PoolFailure
-  wrapEvent = PoolEvent
 
 instance
   ( Era era,
@@ -210,4 +206,3 @@ instance
   Embed (DELEG era) (DELPL era)
   where
   wrapFailed = DelegFailure
-  wrapEvent = DelegEvent
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Epoch.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Epoch.hs
index 4d64bc49cc..dc6fec09af 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Epoch.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Epoch.hs
@@ -114,10 +114,6 @@ instance
   type Environment (EPOCH era) = ()
   type BaseM (EPOCH era) = ShelleyBase
   type PredicateFailure (EPOCH era) = EpochPredicateFailure era
-  data Event _
-    = SnapEvent (Event (SNAP era))
-    | PoolReapEvent (Event (POOLREAP era))
-    | UpecEvents (Event (UPEC era))
   transitionRules = [epochTransition]
 
 instance
@@ -210,7 +206,6 @@ instance
   Embed (SNAP era) (EPOCH era)
   where
   wrapFailed = SnapFailure
-  wrapEvent = SnapEvent
 
 instance
   ( Era era,
@@ -220,7 +215,6 @@ instance
   Embed (POOLREAP era) (EPOCH era)
   where
   wrapFailed = PoolReapFailure
-  wrapEvent = PoolReapEvent
 
 instance
   ( Era era,
@@ -230,4 +224,3 @@ instance
   Embed (UPEC era) (EPOCH era)
   where
   wrapFailed = UpecFailure
-  wrapEvent = UpecEvents
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Ledger.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Ledger.hs
index 401cb3d851..8aaf611758 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Ledger.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Ledger.hs
@@ -19,7 +19,6 @@ module Shelley.Spec.Ledger.STS.Ledger
   ( LEDGER,
     LedgerEnv (..),
     LedgerPredicateFailure (..),
-    Event (..),
     PredicateFailure,
   )
 where
@@ -163,9 +162,6 @@ instance
   type Environment (LEDGER era) = LedgerEnv era
   type BaseM (LEDGER era) = ShelleyBase
   type PredicateFailure (LEDGER era) = LedgerPredicateFailure era
-  data Event _
-    = UtxowEvent (Event (Core.EraRule "UTXOW" era))
-    | DelegsEvent (Event (DELEGS era))
 
   initialRules = []
   transitionRules = [ledgerTransition]
@@ -233,15 +229,12 @@ instance
   Embed (DELEGS era) (LEDGER era)
   where
   wrapFailed = DelegsFailure
-  wrapEvent = DelegsEvent
 
 instance
   ( Era era,
     STS (UTXOW era),
-    PredicateFailure (Core.EraRule "UTXOW" era) ~ UtxowPredicateFailure era,
-    Event (Core.EraRule "UTXOW" era) ~ Event (UTXOW era)
+    PredicateFailure (Core.EraRule "UTXOW" era) ~ UtxowPredicateFailure era
   ) =>
   Embed (UTXOW era) (LEDGER era)
   where
   wrapFailed = UtxowFailure
-  wrapEvent = UtxowEvent
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Ledgers.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Ledgers.hs
index 4bf7784894..c2bf099b2d 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Ledgers.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Ledgers.hs
@@ -118,7 +118,6 @@ instance
   type Environment (LEDGERS era) = LedgersEnv era
   type BaseM (LEDGERS era) = ShelleyBase
   type PredicateFailure (LEDGERS era) = LedgersPredicateFailure era
-  data Event _ = LedgerEvent (Event (LEDGER era))
 
   transitionRules = [ledgersTransition]
 
@@ -153,4 +152,3 @@ instance
   Embed (LEDGER era) (LEDGERS era)
   where
   wrapFailed = LedgerFailure
-  wrapEvent = LedgerEvent
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Mir.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Mir.hs
index 53fde607f7..7aeb7abc27 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Mir.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Mir.hs
@@ -67,7 +67,6 @@ instance (Typeable era, Default (EpochState era)) => STS (MIR era) where
   type Environment (MIR era) = ()
   type BaseM (MIR era) = ShelleyBase
   type PredicateFailure (MIR era) = MirPredicateFailure era
-  data Event _
 
   transitionRules = [mirTransition]
 
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/NewEpoch.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/NewEpoch.hs
index d79226997c..5aa777b446 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/NewEpoch.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/NewEpoch.hs
@@ -98,10 +98,6 @@ instance
   type BaseM (NEWEPOCH era) = ShelleyBase
   type PredicateFailure (NEWEPOCH era) = NewEpochPredicateFailure era
 
-  data Event _
-    = EpochEvent (Event (EPOCH era))
-    | MirEvent (Event (MIR era))
-
   initialRules =
     [ pure $
         NewEpochState
@@ -190,7 +186,6 @@ instance
   Embed (EPOCH era) (NEWEPOCH era)
   where
   wrapFailed = EpochFailure
-  wrapEvent = EpochEvent
 
 instance
   ( Era era,
@@ -200,4 +195,3 @@ instance
   Embed (MIR era) (NEWEPOCH era)
   where
   wrapFailed = MirFailure
-  wrapEvent = MirEvent
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Newpp.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Newpp.hs
index 6649f2d39d..cf219c176a 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Newpp.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Newpp.hs
@@ -93,7 +93,6 @@ instance
   type Environment (NEWPP era) = NewppEnv era
   type BaseM (NEWPP era) = ShelleyBase
   type PredicateFailure (NEWPP era) = NewppPredicateFailure era
-  data Event _
   transitionRules = [newPpTransition]
 
 instance Default (Core.PParams era) => Default (NewppState era) where
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Ocert.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Ocert.hs
index 7341056356..16e0498a94 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Ocert.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Ocert.hs
@@ -71,7 +71,6 @@ instance
   type Environment (OCERT crypto) = OCertEnv crypto
   type BaseM (OCERT crypto) = ShelleyBase
   type PredicateFailure (OCERT crypto) = OcertPredicateFailure crypto
-  data Event _
 
   initialRules = [pure Map.empty]
   transitionRules = [ocertTransition]
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Overlay.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Overlay.hs
index 91fc77014d..953d0c6306 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Overlay.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Overlay.hs
@@ -142,9 +142,6 @@ instance
   type BaseM (OVERLAY crypto) = ShelleyBase
   type PredicateFailure (OVERLAY crypto) = OverlayPredicateFailure crypto
 
-  data Event (OVERLAY crypto)
-    = OcertEvent (Event (OCERT crypto))
-
   initialRules = []
 
   transitionRules = [overlayTransition]
@@ -296,4 +293,3 @@ instance
   Embed (OCERT crypto) (OVERLAY crypto)
   where
   wrapFailed = OcertFailure
-  wrapEvent = OcertEvent
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Pool.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Pool.hs
index e69a0a42f8..918854a944 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Pool.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Pool.hs
@@ -40,7 +40,6 @@ import Control.State.Transition
     failBecause,
     judgmentContext,
     liftSTS,
-    tellEvent,
     (?!),
   )
 import Data.Kind (Type)
@@ -105,10 +104,6 @@ instance
   type BaseM (POOL era) = ShelleyBase
   type PredicateFailure (POOL era) = PoolPredicateFailure era
 
-  data Event (POOL era)
-    = NewPoolParam
-    | NewFuturePoolParam
-
   transitionRules = [poolDelegationTransition]
 
 instance
@@ -181,15 +176,13 @@ poolDelegationTransition = do
 
       let hk = _poolId poolParam
       if eval (hk ∉ dom stpools)
-        then do
-          -- register new, Pool-Reg
-          tellEvent NewPoolParam
+        then -- register new, Pool-Reg
+
           pure $
             ps
               { _pParams = eval (_pParams ps ∪ singleton hk poolParam)
               }
         else do
-          tellEvent NewFuturePoolParam
           pure $
             ps
               { _fPParams = eval (_fPParams ps ⨃ singleton hk poolParam),
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/PoolReap.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/PoolReap.hs
index 621b269fdd..7130bed161 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/PoolReap.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/PoolReap.hs
@@ -86,7 +86,6 @@ instance
   type Environment (POOLREAP era) = Core.PParams era
   type BaseM (POOLREAP era) = ShelleyBase
   type PredicateFailure (POOLREAP era) = PoolreapPredicateFailure era
-  data Event _
   transitionRules = [poolReapTransition]
   assertions =
     [ PostCondition
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Ppup.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Ppup.hs
index 84061f764b..a572352622 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Ppup.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Ppup.hs
@@ -92,7 +92,6 @@ instance
   type Environment (PPUP era) = PPUPEnv era
   type BaseM (PPUP era) = ShelleyBase
   type PredicateFailure (PPUP era) = PpupPredicateFailure era
-  data Event _
 
   initialRules = []
 
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Prtcl.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Prtcl.hs
index c060691615..0f745662a5 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Prtcl.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Prtcl.hs
@@ -148,10 +148,6 @@ instance
   type BaseM (PRTCL crypto) = ShelleyBase
   type PredicateFailure (PRTCL crypto) = PrtclPredicateFailure crypto
 
-  data Event _
-    = OverlayEvent (Event (OVERLAY crypto))
-    | UpdnEvent (Event (UPDN crypto))
-
   initialRules = []
 
   transitionRules = [prtclTransition]
@@ -203,7 +199,6 @@ instance
   Embed (OVERLAY crypto) (PRTCL crypto)
   where
   wrapFailed = OverlayFailure
-  wrapEvent = OverlayEvent
 
 instance
   ( Crypto crypto,
@@ -214,7 +209,6 @@ instance
   Embed (UPDN crypto) (PRTCL crypto)
   where
   wrapFailed = UpdnFailure
-  wrapEvent = UpdnEvent
 
 data PrtlSeqFailure crypto
   = WrongSlotIntervalPrtclSeq
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Rupd.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Rupd.hs
index ddddfc7a1e..18fc646274 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Rupd.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Rupd.hs
@@ -98,7 +98,6 @@ instance
   type Environment (RUPD era) = RupdEnv era
   type BaseM (RUPD era) = ShelleyBase
   type PredicateFailure (RUPD era) = RupdPredicateFailure era
-  data Event _
 
   initialRules = [pure SNothing]
   transitionRules = [rupdTransition]
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Snap.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Snap.hs
index f0861f5ae4..82e45698be 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Snap.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Snap.hs
@@ -49,7 +49,6 @@ instance (UsesTxOut era, UsesValue era) => STS (SNAP era) where
   type Environment (SNAP era) = LedgerState era
   type BaseM (SNAP era) = ShelleyBase
   type PredicateFailure (SNAP era) = SnapPredicateFailure era
-  data Event _
   initialRules = [pure emptySnapShots]
   transitionRules = [snapTransition]
 
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Tick.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Tick.hs
index bb37cd22fd..41e41f9955 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Tick.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Tick.hs
@@ -91,9 +91,6 @@ instance
   type Environment (TICK era) = ()
   type BaseM (TICK era) = ShelleyBase
   type PredicateFailure (TICK era) = TickPredicateFailure era
-  data Event _
-    = NewEpochEvent (Event (NEWEPOCH era))
-    | RupdEvent (Event (RUPD era))
 
   initialRules = []
   transitionRules = [bheadTransition]
@@ -195,7 +192,6 @@ instance
   Embed (NEWEPOCH era) (TICK era)
   where
   wrapFailed = NewEpochFailure
-  wrapEvent = NewEpochEvent
 
 instance
   ( Era era,
@@ -205,7 +201,6 @@ instance
   Embed (RUPD era) (TICK era)
   where
   wrapFailed = RupdFailure
-  wrapEvent = RupdEvent
 
 {------------------------------------------------------------------------------
 -- TICKF transition
@@ -257,8 +252,6 @@ instance
   type Environment (TICKF era) = ()
   type BaseM (TICKF era) = ShelleyBase
   type PredicateFailure (TICKF era) = TickfPredicateFailure era
-  data Event _
-    = TickfNewEpochEvent (Event (NEWEPOCH era))
 
   initialRules = []
   transitionRules =
@@ -277,4 +270,3 @@ instance
   Embed (NEWEPOCH era) (TICKF era)
   where
   wrapFailed = TickfNewEpochFailure
-  wrapEvent = TickfNewEpochEvent
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Tickn.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Tickn.hs
index 2848690d6e..48cf9deff7 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Tickn.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Tickn.hs
@@ -73,7 +73,6 @@ instance STS TICKN where
   type Environment TICKN = TicknEnv
   type BaseM TICKN = ShelleyBase
   type PredicateFailure TICKN = TicknPredicateFailure
-  data Event _
 
   initialRules =
     [ pure
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Updn.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Updn.hs
index 57a0f2aed0..470b41bb58 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Updn.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Updn.hs
@@ -48,7 +48,6 @@ instance
   type Environment (UPDN crypto) = UpdnEnv
   type BaseM (UPDN crypto) = ShelleyBase
   type PredicateFailure (UPDN crypto) = UpdnPredicateFailure crypto
-  data Event _
   initialRules =
     [ pure
         ( UpdnState
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Upec.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Upec.hs
index 85633f0dae..018d9b0581 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Upec.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Upec.hs
@@ -91,8 +91,6 @@ instance
   type Environment (UPEC era) = EpochState era
   type BaseM (UPEC era) = ShelleyBase
   type PredicateFailure (UPEC era) = UpecPredicateFailure era
-  data Event (UPEC era)
-    = NewPpEvent (Event (NEWPP era))
   initialRules = []
   transitionRules =
     [ do
@@ -158,4 +156,3 @@ instance
   Embed (NEWPP era) (UPEC era)
   where
   wrapFailed = NewPpFailure
-  wrapEvent = NewPpEvent
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Utxo.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Utxo.hs
index cfe1129a64..d3b46d1ac6 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Utxo.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Utxo.hs
@@ -73,7 +73,6 @@ import Control.State.Transition
     judgmentContext,
     liftSTS,
     trans,
-    wrapEvent,
     wrapFailed,
     (?!),
   )
@@ -296,7 +295,6 @@ instance
   type Environment (UTXO era) = UtxoEnv era
   type BaseM (UTXO era) = ShelleyBase
   type PredicateFailure (UTXO era) = UtxoPredicateFailure era
-  data Event _ = UpdateEvent (Event (PPUP era))
 
   transitionRules = [utxoInductive]
 
@@ -440,4 +438,3 @@ instance
   Embed (PPUP era) (UTXO era)
   where
   wrapFailed = UpdateFailure
-  wrapEvent = UpdateEvent
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Utxow.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Utxow.hs
index 799ae7fb37..0660ea1faf 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Utxow.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/STS/Utxow.hs
@@ -75,7 +75,6 @@ import Control.State.Transition
     judgmentContext,
     liftSTS,
     trans,
-    wrapEvent,
     wrapFailed,
     (?!),
     (?!:),
@@ -388,7 +387,6 @@ instance
   Embed (UTXO era) (UTXOW era)
   where
   wrapFailed = UtxoFailure
-  wrapEvent = UtxoEvent
 
 instance
   ( -- Fix Core.Witnesses to the Shelley Era
@@ -411,6 +409,5 @@ instance
   type Environment (UTXOW era) = UtxoEnv era
   type BaseM (UTXOW era) = ShelleyBase
   type PredicateFailure (UTXOW era) = UtxowPredicateFailure era
-  data Event _ = UtxoEvent (Event (UTXO era))
   transitionRules = [shelleyStyleWitness witsVKeyNeeded id]
   initialRules = [initialLedgerStateUTXOW]
diff --git a/shelley/chain-and-ledger/shelley-spec-ledger-test/src/Test/Shelley/Spec/Ledger/Generator/Trace/DCert.hs b/shelley/chain-and-ledger/shelley-spec-ledger-test/src/Test/Shelley/Spec/Ledger/Generator/Trace/DCert.hs
index 22979d4622..995c586e86 100644
--- a/shelley/chain-and-ledger/shelley-spec-ledger-test/src/Test/Shelley/Spec/Ledger/Generator/Trace/DCert.hs
+++ b/shelley/chain-and-ledger/shelley-spec-ledger-test/src/Test/Shelley/Spec/Ledger/Generator/Trace/DCert.hs
@@ -31,7 +31,6 @@ import Control.State.Transition
     Environment,
     PredicateFailure,
     STS,
-    Event,
     Signal,
     State,
     TRC (..),
@@ -40,7 +39,7 @@ import Control.State.Transition
     judgmentContext,
     trans,
     transitionRules,
-    wrapFailed, wrapEvent
+    wrapFailed,
   )
 import Control.State.Transition.Trace (TraceOrder (OldestFirst), lastState, traceSignals)
 import qualified Control.State.Transition.Trace.Generator.QuickCheck as QC
@@ -114,8 +113,6 @@ instance
 
   type BaseM (CERTS era) = ShelleyBase
 
-  data Event _ = DELPLEvent (Event (DELPL era))
-
   initialRules = []
   transitionRules = [certsTransition]
 
@@ -154,7 +151,6 @@ instance
   Embed (DELPL era) (CERTS era)
   where
   wrapFailed = CertsFailure
-  wrapEvent = DELPLEvent
 
 instance
   ( EraGen era,
diff --git a/shelley/chain-and-ledger/shelley-spec-ledger-test/src/Test/Shelley/Spec/Ledger/Utils.hs b/shelley/chain-and-ledger/shelley-spec-ledger-test/src/Test/Shelley/Spec/Ledger/Utils.hs
index 4ef8fca3b6..c34f47b88f 100644
--- a/shelley/chain-and-ledger/shelley-spec-ledger-test/src/Test/Shelley/Spec/Ledger/Utils.hs
+++ b/shelley/chain-and-ledger/shelley-spec-ledger-test/src/Test/Shelley/Spec/Ledger/Utils.hs
@@ -330,7 +330,7 @@ applySTSTest ::
   RuleContext rtype s ->
   m (Either [[PredicateFailure s]] (State s))
 applySTSTest ctx =
-  applySTSOpts EPDiscard defaultOpts ctx <&> \case
+  applySTSOpts defaultOpts ctx <&> \case
     (st, []) -> Right st
     (_, pfs) -> Left pfs
   where