diff --git a/src/proto_alpha/lib_protocol/validate.ml b/src/proto_alpha/lib_protocol/validate.ml
index bc0220e6e78e73419f43314b00d475945718bf72..d36bec58a7213fd39122db82aa282030fc928671 100644
--- a/src/proto_alpha/lib_protocol/validate.ml
+++ b/src/proto_alpha/lib_protocol/validate.ml
@@ -1675,8 +1675,13 @@ module Anonymous = struct
     in
     match dal_content with
     | None ->
-        (* TODO: return error *)
-        failwith "Wrong evidence: the attester did not DAL attest"
+        tzfail
+          (Invalid_accusation_no_dal_content
+             {
+               tb_slot = consensus_content.slot;
+               level = consensus_content.level;
+               slot_index;
+             })
     | Some dal_content -> (
         let number_of_slots = Constants.dal_number_of_slots vi.ctxt in
         let*? () =
@@ -1687,12 +1692,13 @@ module Anonymous = struct
         let*? () =
           check_shard_index_is_in_range ~number_of_shards shard_index
         in
-        assert (
-          (* TODO: check and return error *)
-          Dal.Attestation.is_attested
-            dal_content.attestation
-            slot_index) ;
         let level = consensus_content.level in
+        let*? () =
+          error_unless
+            (Dal.Attestation.is_attested dal_content.attestation slot_index)
+            (Invalid_accusation_slot_not_attested
+               {tb_slot = consensus_content.slot; level; slot_index})
+        in
         let* protocol_first_level = First_level_of_protocol.get vi.ctxt in
         let*? () =
           (* Due to the DAL node possibly not checking for traps before the R
@@ -1721,7 +1727,7 @@ module Anonymous = struct
         let*? () =
           error_unless
             (not already_denounced)
-            (Dal_already_denounced {delegate; level})
+            (Dal_already_denounced {delegate; level = level.level})
         in
         let traps_fraction = (Constants.parametric ctxt).dal.traps_fraction in
         let*? is_trap =
@@ -1730,27 +1736,44 @@ module Anonymous = struct
             shard_with_proof.shard.share
             ~traps_fraction
         in
-        assert (* TODO: check and return error *)
-               is_trap ;
+        let*? () =
+          error_unless
+            is_trap
+            (Invalid_accusation_shard_is_not_trap
+               {
+                 delegate;
+                 level = level.level;
+                 slot_index;
+                 shard_index = shard_with_proof.shard.index;
+               })
+        in
         let* _ctxt, shard_owner =
           let*? tb_slot = Slot.of_int shard_index in
           Stake_distribution.slot_owner vi.ctxt level tb_slot
         in
-        assert (
-          (* TODO: check and return error *)
-          Signature.Public_key_hash.equal
-            delegate
-            shard_owner.delegate) ;
+        let*? () =
+          error_unless
+            (Signature.Public_key_hash.equal delegate shard_owner.delegate)
+            (Invalid_accusation_wrong_shard_owner
+               {
+                 delegate;
+                 level = level.level;
+                 slot_index;
+                 shard_index = shard_with_proof.shard.index;
+                 shard_owner = shard_owner.delegate;
+               })
+        in
         let attestation_lag =
           (Constants.parametric vi.ctxt).dal.attestation_lag
         in
-        let published_level =
+        let* published_level =
           match Raw_level.(sub (succ level.level) attestation_lag) with
           | None ->
-              failwith
-                "SHOULD NOT HAPPEN ON MAINNET. It can in theory happen on test \
-                 networks (but it is very unlikely)"
-          | Some level -> level
+              (* The slot couldn't have been published in this case *)
+              tzfail
+                (Invalid_accusation_slot_not_published
+                   {delegate; level = level.level; slot_index})
+          | Some level -> return level
         in
         let* slot_headers_opt =
           Dal.Slot.find_slot_headers ctxt published_level
@@ -1759,9 +1782,11 @@ module Anonymous = struct
         | None ->
             (* TODO: https://gitlab.com/tezos/tezos/-/issues/7126
                Can also fail if `attestation_lag` changes. *)
-            failwith (* TODO: return error *)
-              "SHOULD NOT HAPPEN IF 1) the denunciation age is correct, and 2) \
-               the storage is updated correctly"
+            (* It should not happen if 1) the denunciation age is correct, and 2) \
+               the storage is updated correctly *)
+            tzfail
+              (Accusation_validity_error_cannot_get_slot_headers
+                 {delegate; level = level.level; slot_index})
         | Some headers -> (
             let slot_header_opt =
               List.find
@@ -1786,18 +1811,24 @@ module Anonymous = struct
                     attestation
                 in
                 return_unit
-            | Some _ ->
+            | Some (header, _publisher) ->
                 (* TODO: https://gitlab.com/tezos/tezos/-/issues/7126
                    Can also fail if `attestation_lag` changes. *)
-                (* TODO: return error *)
-                failwith
-                  "SHOULD NOT HAPPEN: mismatch between published levels in \
-                   storage versus in evidence"
+                (* mismatch between published levels in \
+                   storage versus in evidence; it should not happen *)
+                tzfail
+                  (Accusation_validity_error_levels_mismatch
+                     {
+                       delegate;
+                       level = level.level;
+                       slot_index;
+                       accusation_published_level = published_level;
+                       store_published_level = header.id.published_level;
+                     })
             | None ->
-                (* TODO: return error *)
-                failwith
-                  "Wrong evidence: no slot was published at the mentioned \
-                   level and index"))
+                tzfail
+                  (Invalid_accusation_slot_not_published
+                     {delegate; level = level.level; slot_index})))
 
   let check_dal_entrapment_evidence vi
       (operation : Kind.dal_entrapment_evidence operation) =
diff --git a/src/proto_alpha/lib_protocol/validate_errors.ml b/src/proto_alpha/lib_protocol/validate_errors.ml
index dc59f2460e682cc982eb851c81c9926ea9bb954b..7b48f864b66eef1429ccc2f526d6a61e3e127069 100644
--- a/src/proto_alpha/lib_protocol/validate_errors.ml
+++ b/src/proto_alpha/lib_protocol/validate_errors.ml
@@ -899,12 +899,52 @@ module Anonymous = struct
     | Invalid_shard_index of {given : int; min : int; max : int}
     | Dal_already_denounced of {
         delegate : Signature.Public_key_hash.t;
-        level : Level.t;
+        level : Raw_level.t;
       }
     | Denunciations_not_allowed_just_after_migration of {
         level : Raw_level.t;
         first_allowed_level : Raw_level.t;
       }
+    | Invalid_accusation_no_dal_content of {
+        tb_slot : Slot.t;
+        level : Raw_level.t;
+        slot_index : Dal.Slot_index.t;
+      }
+    | Invalid_accusation_slot_not_attested of {
+        tb_slot : Slot.t;
+        level : Raw_level.t;
+        slot_index : Dal.Slot_index.t;
+      }
+    | Invalid_accusation_shard_is_not_trap of {
+        delegate : Signature.Public_key_hash.t;
+        level : Raw_level.t;
+        slot_index : Dal.Slot_index.t;
+        shard_index : int;
+      }
+    | Invalid_accusation_wrong_shard_owner of {
+        delegate : Signature.Public_key_hash.t;
+        level : Raw_level.t;
+        slot_index : Dal.Slot_index.t;
+        shard_index : int;
+        shard_owner : Signature.Public_key_hash.t;
+      }
+    | Invalid_accusation_slot_not_published of {
+        delegate : Signature.Public_key_hash.t;
+        level : Raw_level.t;
+        slot_index : Dal.Slot_index.t;
+      }
+    | Accusation_validity_error_cannot_get_slot_headers of {
+        delegate : Signature.Public_key_hash.t;
+        level : Raw_level.t;
+        slot_index : Dal.Slot_index.t;
+      }
+    | Accusation_validity_error_levels_mismatch of {
+        delegate : Signature.Public_key_hash.t;
+        level : Raw_level.t;
+        slot_index : Dal.Slot_index.t;
+        accusation_published_level : Raw_level.t;
+        store_published_level : Raw_level.t;
+      }
     | Conflicting_dal_entrapment of operation_conflict
 
   let () =
@@ -979,11 +1019,11 @@ module Anonymous = struct
            entrapment."
           Signature.Public_key_hash.pp
           delegate
-          Level.pp
+          Raw_level.pp
           level)
       (obj2
          (req "delegate" Signature.Public_key_hash.encoding)
-         (req "level" Level.encoding))
+         (req "level" Raw_level.encoding))
       (function
         | Dal_already_denounced {delegate; level} -> Some (delegate, level)
         | _ -> None)
@@ -1016,6 +1056,247 @@ module Anonymous = struct
         Denunciations_not_allowed_just_after_migration
           {level; first_allowed_level}) ;
 
+    register_error_kind
+      `Permanent
+      ~id:"validate.operation.invalid_accusation_no_dal_content"
+      ~title:"Invalid accusation: no DAL content"
+      ~description:
+        "Invalid accusation: the attestation operation has no DAL content."
+      ~pp:(fun ppf (tb_slot, level, slot_index) ->
+        Format.fprintf
+          ppf
+          "Invalid accusation for validator slot %a, level %a, and DAL slot \
+           index %a: the attestation operation has no DAL content."
+          Slot.pp
+          tb_slot
+          Raw_level.pp
+          level
+          Dal.Slot_index.pp
+          slot_index)
+      (obj3
+         (req "TB_slot" Slot.encoding)
+         (req "level" Raw_level.encoding)
+         (req "slot_index" Dal.Slot_index.encoding))
+      (function
+        | Invalid_accusation_no_dal_content {tb_slot; level; slot_index} ->
+            Some (tb_slot, level, slot_index)
+        | _ -> None)
+      (fun (tb_slot, level, slot_index) ->
+        Invalid_accusation_no_dal_content {tb_slot; level; slot_index}) ;
+    register_error_kind
+      `Permanent
+      ~id:"validate.operation.invalid_accusation_slot_not_attested"
+      ~title:"Invalid accusation: the delegate did not attest the DAL slot"
+      ~description:
+        "Invalid accusation: the delegate did not attest the DAL slot."
+      ~pp:(fun ppf (tb_slot, level, slot_index) ->
+        Format.fprintf
+          ppf
+          "Invalid accusation for validator slot %a, level %a, and DAL slot \
+           index %a: the delegate did not attest the DAL slot."
+          Slot.pp
+          tb_slot
+          Raw_level.pp
+          level
+          Dal.Slot_index.pp
+          slot_index)
+      (obj3
+         (req "TB_slot" Slot.encoding)
+         (req "level" Raw_level.encoding)
+         (req "slot_index" Dal.Slot_index.encoding))
+      (function
+        | Invalid_accusation_slot_not_attested {tb_slot; level; slot_index} ->
+            Some (tb_slot, level, slot_index)
+        | _ -> None)
+      (fun (tb_slot, level, slot_index) ->
+        Invalid_accusation_slot_not_attested {tb_slot; level; slot_index}) ;
+    register_error_kind
+      `Permanent
+      ~id:"validate.operation.invalid_accusation_shard_is_not_trap"
+      ~title:"Invalid accusation: the provided shard is not a trap"
+      ~description:"Invalid accusation: the provided shard is not a trap."
+      ~pp:(fun ppf (delegate, level, slot_index, shard_index) ->
+        Format.fprintf
+          ppf
+          "Invalid accusation for delegate %a, level %a, DAL slot index %a, \
+           and shard index %d: the provided shard is not a trap."
+          Signature.Public_key_hash.pp
+          delegate
+          Raw_level.pp
+          level
+          Dal.Slot_index.pp
+          slot_index
+          shard_index)
+      (obj4
+         (req "delegate" Signature.Public_key_hash.encoding)
+         (req "level" Raw_level.encoding)
+         (req "slot_index" Dal.Slot_index.encoding)
+         (req "shard_index" int31))
+      (function
+        | Invalid_accusation_shard_is_not_trap
+            {delegate; level; slot_index; shard_index} ->
+            Some (delegate, level, slot_index, shard_index)
+        | _ -> None)
+      (fun (delegate, level, slot_index, shard_index) ->
+        Invalid_accusation_shard_is_not_trap
+          {delegate; level; slot_index; shard_index}) ;
+    register_error_kind
+      `Permanent
+      ~id:"validate.operation.invalid_accusation_wrong_shard_owner"
+      ~title:
+        "Invalid accusation: the provided shard is not assigned to the attester"
+      ~description:
+        "Invalid accusation: the provided shard is not assigned to the \
+         attester."
+      ~pp:(fun ppf (delegate, level, slot_index, shard_index, shard_owner) ->
+        Format.fprintf
+          ppf
+          "Invalid accusation for delegate %a, level %a, DAL slot index %a, \
+           and shard index %d: the shard is assigned to %a, not the attester."
+          Signature.Public_key_hash.pp
+          delegate
+          Raw_level.pp
+          level
+          Dal.Slot_index.pp
+          slot_index
+          shard_index
+          Signature.Public_key_hash.pp
+          shard_owner)
+      (obj5
+         (req "delegate" Signature.Public_key_hash.encoding)
+         (req "level" Raw_level.encoding)
+         (req "slot_index" Dal.Slot_index.encoding)
+         (req "shard_index" Data_encoding.int31)
+         (req "shard_owner" Signature.Public_key_hash.encoding))
+      (function
+        | Invalid_accusation_wrong_shard_owner
+            {delegate; level; slot_index; shard_index; shard_owner} ->
+            Some (delegate, level, slot_index, shard_index, shard_owner)
+        | _ -> None)
+      (fun (delegate, level, slot_index, shard_index, shard_owner) ->
+        Invalid_accusation_wrong_shard_owner
+          {delegate; level; slot_index; shard_index; shard_owner}) ;
+    register_error_kind
+      `Permanent
+      ~id:"validate.operation.invalid_accusation_slot_not_published"
+      ~title:"Invalid accusation: DAL slot not published"
+      ~description:"Invalid accusation: the DAL slot was not published."
+      ~pp:(fun ppf (delegate, level, slot_index) ->
+        Format.fprintf
+          ppf
+          "Invalid accusation for delegate %a, level %a, and DAL slot index \
+           %a: the DAL slot was not published."
+          Signature.Public_key_hash.pp
+          delegate
+          Raw_level.pp
+          level
+          Dal.Slot_index.pp
+          slot_index)
+      (obj3
+         (req "delegate" Signature.Public_key_hash.encoding)
+         (req "level" Raw_level.encoding)
+         (req "slot_index" Dal.Slot_index.encoding))
+      (function
+        | Invalid_accusation_slot_not_published {delegate; level; slot_index} ->
+            Some (delegate, level, slot_index)
+        | _ -> None)
+      (fun (delegate, level, slot_index) ->
+        Invalid_accusation_slot_not_published {delegate; level; slot_index}) ;
+    register_error_kind
+      `Permanent
+      ~id:"validate.operation.accusation_validity_error_cannot_get_slot_headers"
+      ~title:"Accusation validity error: cannot get slot headers"
+      ~description:
+        "Accusation validity internal error: unable to retrieve the required \
+         DAL slot headers."
+      ~pp:(fun ppf (delegate, level, slot_index) ->
+        Format.fprintf
+          ppf
+          "Accusation validity internal error for delegate %a, level %a, and \
+           DAL slot index %a: unable to retrieve the required slot headers."
+          Signature.Public_key_hash.pp
+          delegate
+          Raw_level.pp
+          level
+          Dal.Slot_index.pp
+          slot_index)
+      (obj3
+         (req "delegate" Signature.Public_key_hash.encoding)
+         (req "level" Raw_level.encoding)
+         (req "slot_index" Dal.Slot_index.encoding))
+      (function
+        | Accusation_validity_error_cannot_get_slot_headers
+            {delegate; level; slot_index} ->
+            Some (delegate, level, slot_index)
+        | _ -> None)
+      (fun (delegate, level, slot_index) ->
+        Accusation_validity_error_cannot_get_slot_headers
+          {delegate; level; slot_index}) ;
+    register_error_kind
+      `Permanent
+      ~id:"validate.operation.accusation_validity_error_levels_mismatch"
+      ~title:"Accusation validity internal error: levels mismatch"
+      ~description:
+        "Accusation validity internal error: mismatch between published levels \
+         in storage and evidence."
+      ~pp:(fun
+          ppf
+          ( delegate,
+            level,
+            slot_index,
+            accusation_published_level,
+            store_published_level )
+        ->
+        Format.fprintf
+          ppf
+          "Accusation validity error for delegate %a, level %a, and DAL slot \
+           index %a: mismatch between published levels in evidence (%a) and \
+           storage (%a)."
+          Signature.Public_key_hash.pp
+          delegate
+          Raw_level.pp
+          level
+          Dal.Slot_index.pp
+          slot_index
+          Raw_level.pp
+          accusation_published_level
+          Raw_level.pp
+          store_published_level)
+      (obj5
+         (req "delegate" Signature.Public_key_hash.encoding)
+         (req "level" Raw_level.encoding)
+         (req "slot_index" Dal.Slot_index.encoding)
+         (req "accusation_published_level" Raw_level.encoding)
+         (req "store_published_level" Raw_level.encoding))
+      (function
+        | Accusation_validity_error_levels_mismatch
+            {
+              delegate;
+              level;
+              slot_index;
+              accusation_published_level;
+              store_published_level;
+            } ->
+            Some
+              ( delegate,
+                level,
+                slot_index,
+                accusation_published_level,
+                store_published_level )
+        | _ -> None)
+      (fun ( delegate,
+             level,
+             slot_index,
+             accusation_published_level,
+             store_published_level ) ->
+        Accusation_validity_error_levels_mismatch
+          {
+            delegate;
+            level;
+            slot_index;
+            accusation_published_level;
+            store_published_level;
+          }) ;
     register_error_kind
       `Branch
       ~id:"validate.operation.conflicting_dal_entrapment"
diff --git a/src/proto_alpha/lib_protocol/validate_errors.mli b/src/proto_alpha/lib_protocol/validate_errors.mli
index 7ec53da75fe9fb3cf3839641ef0bed049e402fa9..1dbeb5fd03e466cadaca9aafcc6c22a7fcd06614 100644
--- a/src/proto_alpha/lib_protocol/validate_errors.mli
+++ b/src/proto_alpha/lib_protocol/validate_errors.mli
@@ -160,12 +160,52 @@ module Anonymous : sig
     | Invalid_shard_index of {given : int; min : int; max : int}
     | Dal_already_denounced of {
         delegate : Signature.Public_key_hash.t;
-        level : Level.t;
+        level : Raw_level.t;
       }
     | Denunciations_not_allowed_just_after_migration of {
         level : Raw_level.t;
         first_allowed_level : Raw_level.t;
       }
+    | Invalid_accusation_no_dal_content of {
+        tb_slot : Slot.t;
+        level : Raw_level.t;
+        slot_index : Dal.Slot_index.t;
+      }
+    | Invalid_accusation_slot_not_attested of {
+        tb_slot : Slot.t;
+        level : Raw_level.t;
+        slot_index : Dal.Slot_index.t;
+      }
+    | Invalid_accusation_shard_is_not_trap of {
+        delegate : Signature.Public_key_hash.t;
+        level : Raw_level.t;
+        slot_index : Dal.Slot_index.t;
+        shard_index : int;
+      }
+    | Invalid_accusation_wrong_shard_owner of {
+        delegate : Signature.Public_key_hash.t;
+        level : Raw_level.t;
+        slot_index : Dal.Slot_index.t;
+        shard_index : int;
+        shard_owner : Signature.Public_key_hash.t;
+      }
+    | Invalid_accusation_slot_not_published of {
+        delegate : Signature.Public_key_hash.t;
+        level : Raw_level.t;
+        slot_index : Dal.Slot_index.t;
+      }
+    | Accusation_validity_error_cannot_get_slot_headers of {
+        delegate : Signature.Public_key_hash.t;
+        level : Raw_level.t;
+        slot_index : Dal.Slot_index.t;
+      }
+    | Accusation_validity_error_levels_mismatch of {
+        delegate : Signature.Public_key_hash.t;
+        level : Raw_level.t;
+        slot_index : Dal.Slot_index.t;
+        accusation_published_level : Raw_level.t;
+        store_published_level : Raw_level.t;
+      }
     | Conflicting_dal_entrapment of operation_conflict
     | Conflicting_nonce_revelation of operation_conflict
     | Conflicting_vdf_revelation of operation_conflict