What is FOCIL in one sentence?

FOCIL (Fork-Choice enforced Inclusion Lists, EIP-7805) lets a randomly selected committee of validators each propose transactions that the next block MUST include, so a single builder cannot silently censor users.

Is FOCIL live on Ethereum mainnet?

Not yet. As of April 2026, FOCIL is specified as EIP-7805 and is a leading candidate for Ethereum's Glamsterdam hard fork, which is targeted for late 2026. It has been tested on devnets and is undergoing client implementation review.

How is FOCIL different from normal inclusion lists?

Earlier inclusion list designs relied on a single proposer to name the transactions that the next block must include, which meant the proposer could still be bribed or coerced. FOCIL spreads that power across a committee of 16 validators per slot, and the fork-choice rule penalizes blocks that ignore their lists.

Does FOCIL break MEV-Boost or PBS?

No. FOCIL is intentionally designed to coexist with proposer-builder separation and MEV-Boost. Builders still compete on tip extraction, but they must satisfy any non-conflicting transactions named by the FOCIL committee, which restores baseline censorship resistance.

Why does FOCIL matter for ordinary users?

If you use a mixer, a sanctioned address, or simply a dApp that some builders dislike, today your transaction can sit unmined for hours. With FOCIL, at least one of 16 committee members is likely to name your transaction, and the block that follows is forced to include it or lose fork-choice weight.

How does FOCIL relate to based rollups?

Based rollups inherit L1 censorship resistance. A strong FOCIL on Ethereum directly upgrades the censorship resistance of every based rollup and of any L2 that uses force-inclusion via L1 calldata, making the whole stack harder to capture.

EthereumIntermediate10–12 min read·Published April 9, 2026

FOCIL & Inclusion Lists on Ethereum: The 2026 Guide

How EIP-7805 forces builders to stop censoring your transactions — without breaking MEV-Boost, PBS, or the roadmap Ethereum is already on.

Why inclusion lists exist

Since the Merge, almost every Ethereum block has been built by a small group of block builders connected to proposers through MEV-Boost. That design is efficient, but it created a single point of censorship: if the top two or three builders decide to drop a transaction — because of OFAC screening, a private filter, or simple commercial pressure — the average user sees their transaction sit in the mempool for hours. Inclusion lists are the answer: a simple rule that says “the next block MUST contain these transactions, or it is invalid.”

💡Why This Matters

We wrote this guide because the existing explanations online are either too simplified or assume PhD-level knowledge. Neither serves most readers.

Earlier designs, like EIP-7547, gave that power to the slot proposer. But a proposer is a single actor that can be bribed, coerced, or compromised. FOCIL fixes this by spreading the responsibility across a committee of validators.

What FOCIL actually does

FOCIL stands for Fork-Choice enforced Inclusion Lists. It is specified in EIP-7805. Every slot, the beacon chain deterministically selects 16 validators as the inclusion list committee. Each committee member watches the public mempool and publishes a short list of transactions they believe the next block should contain.

When the block proposer and their builder assemble the next payload, they are free to order transactions however they like — the MEV game is preserved. But the payload must satisfy the union of the committee’s lists: every non-conflicting, still-valid transaction named by a committee member has to make it into the block, unless the block is genuinely full. Anything else, and the Ethereum fork-choice rule (the algorithm that decides which head to follow) penalizes the block. Honest attesters will simply refuse to vote for it, and it falls out of the canonical chain.

The critical word is fork-choice enforced. Unlike softer schemes, censoring a FOCIL transaction is not “frowned upon” — it costs the builder the block’s reward.

Why a committee of 16?

Sixteen is the number researchers landed on after modeling two failure cases: a committee too small to be robust, and one too large to be bandwidth-friendly. With 16 independent validators, bribing the entire committee in a single slot is economically irrational for all but the most valuable censorship attempts, while the aggregate list stays small enough to gossip quickly across the network.

Importantly, the committee only needs one honest member for a user’s transaction to be forced in. That is a dramatic asymmetry: attackers must compromise all 16, defenders need only one.

How FOCIL fits the Glamsterdam roadmap

Fusaka shipped in December 2025 with PeerDAS and a raised gas limit. The next hard fork, Glamsterdam, is targeted for late 2026 and is explicitly themed around censorship resistance and user experience. FOCIL is one of the leading candidates for inclusion, alongside enshrined proposer-builder separation (ePBS), MEV burn experiments, and further blob throughput work.

FOCIL is not the final word on censorship resistance — attester-enforced lists and ePBS are still active research — but it is the cleanest near-term upgrade that can ship without rewriting the whole block production pipeline.

What FOCIL means for users, L2s, and builders

For users: if your transaction pays a reasonable tip and touches no forbidden state, at least one of 16 validators is very likely to name it, and the block that follows must include it. Time-to-inclusion for controversial transactions should collapse from hours to a single slot.

For Layer 2s: based rollups, force-inclusion queues, and escape-hatch withdrawals all inherit this property. A strong FOCIL on L1 is the single biggest upgrade to L2 censorship resistance that Ethereum can make without touching the rollups themselves.

For builders: MEV-Boost still works, proposer-builder separation still works, and tip extraction continues. Builders simply lose the ability to silently drop user transactions — a power most honest builders never wanted in the first place.

Open questions

FOCIL still has unresolved design tradeoffs: how to handle conflicting transactions named by different committee members, how to gossip lists fast enough under network stress, and how to prevent spam attacks on the list itself. These are the main topics being worked out on devnets and in all-core-dev calls throughout 2026.

The takeaway for degens: FOCIL is probably the most important thing happening in Ethereum protocol politics this year. Watch the Glamsterdam scope discussions closely.

Frequently asked questions

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