diff --git a/benchmarks/tasm_neptune_transaction_removal_records_integrity.json b/benchmarks/tasm_neptune_transaction_removal_records_integrity.json
index fa9fe7729..f6af9b30e 100644
--- a/benchmarks/tasm_neptune_transaction_removal_records_integrity.json
+++ b/benchmarks/tasm_neptune_transaction_removal_records_integrity.json
@@ -3,7 +3,7 @@
     "name": "tasm_neptune_transaction_removal_records_integrity",
     "clock_cycle_count": 29649,
     "hash_table_height": 5633,
-    "u32_table_height": 13245,
+    "u32_table_height": 13250,
     "case": "CommonCase"
   }
 ]
\ No newline at end of file
diff --git a/src/models/blockchain/block/validity.rs b/src/models/blockchain/block/validity.rs
index 083ea6b62..691f1617f 100644
--- a/src/models/blockchain/block/validity.rs
+++ b/src/models/blockchain/block/validity.rs
@@ -1,26 +1,34 @@
 use get_size::GetSize;
 use serde::{Deserialize, Serialize};
-use tasm_lib::twenty_first;
+use tasm_lib::{
+    triton_vm::program::{NonDeterminism, Program},
+    twenty_first::{self, shared_math::b_field_element::BFieldElement},
+};
 use twenty_first::shared_math::bfield_codec::BFieldCodec;
 
+use crate::models::consensus::SecretWitness;
+
 use self::{
     coinbase_is_valid::CoinbaseIsValid,
     correct_control_parameter_update::CorrectControlParameterUpdate,
     correct_mmr_update::CorrectMmrUpdate, correct_mutator_set_update::CorrectMutatorSetUpdate,
-    predecessor_is_valid::PredecessorIsValid, transaction_is_valid::TransactionIsValid,
+    mmr_membership::MmrMembership, predecessor_is_valid::PredecessorIsValid,
+    transaction_is_valid::TransactionIsValid,
 };
 
+use super::Block;
+
 pub mod coinbase_is_valid;
 pub mod correct_control_parameter_update;
 pub mod correct_mmr_update;
 pub mod correct_mutator_set_update;
+pub mod mmr_membership;
 pub mod predecessor_is_valid;
 pub mod transaction_is_valid;
 
-/// The validity of a block, when it is not the genesis block and when it does not
-/// come with proofs, decomposes into these subclaims.
+/// The validity of a block, in the principal case, decomposes into these subclaims.
 #[derive(Clone, Debug, Serialize, Deserialize, PartialEq, Eq, GetSize, BFieldCodec)]
-pub struct BlockValidationLogic {
+pub struct PrincipalBlockValidationLogic {
     // program: recursive-verify-or-is-genesis, input: block kernel, output: []
     pub predecessor_is_valid: PredecessorIsValid,
 
@@ -39,3 +47,28 @@ pub struct BlockValidationLogic {
     // program: update-control-parameters, input: block kernel, output: []
     pub correct_control_parameter_update: CorrectControlParameterUpdate,
 }
+
+/// Alternatively, the validity of a block follows from that of a successor. This pathway
+/// two subclaims, both of which are relative to the successor block.
+///  1. the current block lives in the block mmr of the successor block
+///  2. the successor block is valid
+#[derive(Clone, Debug, Serialize, Deserialize, PartialEq, Eq, GetSize, BFieldCodec)]
+pub struct AlternativeBlockValidationLogic {
+    pub mmr_membership: MmrMembership,
+    pub successor_is_valid: PrincipalBlockValidationLogic,
+}
+
+#[derive(Debug, Clone, BFieldCodec, GetSize, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PrincipalBlockValidationWitness {
+    pub successor: Block, // includes proof
+}
+
+impl SecretWitness for PrincipalBlockValidationWitness {
+    fn nondeterminism(&self) -> NonDeterminism<BFieldElement> {
+        todo!()
+    }
+
+    fn subprogram(&self) -> Program {
+        todo!()
+    }
+}
diff --git a/src/models/blockchain/block/validity/mmr_membership.rs b/src/models/blockchain/block/validity/mmr_membership.rs
new file mode 100644
index 000000000..160e68713
--- /dev/null
+++ b/src/models/blockchain/block/validity/mmr_membership.rs
@@ -0,0 +1,31 @@
+use crate::models::blockchain::block::BFieldCodec;
+use crate::models::blockchain::block::Deserialize;
+use crate::models::blockchain::block::GetSize;
+use crate::models::blockchain::block::Serialize;
+use crate::models::blockchain::shared::Hash;
+use crate::models::consensus::SecretWitness;
+use crate::models::consensus::SupportedClaim;
+use crate::triton_vm::program::Program;
+use tasm_lib::triton_vm::program::NonDeterminism;
+use tasm_lib::twenty_first::shared_math::b_field_element::BFieldElement;
+use tasm_lib::twenty_first::util_types::mmr::mmr_membership_proof::MmrMembershipProof;
+
+#[derive(Debug, Clone, BFieldCodec, GetSize, PartialEq, Eq, Serialize, Deserialize)]
+pub struct MmrMembershipWitness {
+    pub membership_proof: MmrMembershipProof<Hash>,
+}
+
+impl SecretWitness for MmrMembershipWitness {
+    fn nondeterminism(&self) -> NonDeterminism<BFieldElement> {
+        todo!()
+    }
+
+    fn subprogram(&self) -> Program {
+        todo!()
+    }
+}
+
+#[derive(Debug, Clone, BFieldCodec, GetSize, PartialEq, Eq, Serialize, Deserialize)]
+pub struct MmrMembership {
+    supported_claim: SupportedClaim<MmrMembershipWitness>,
+}