What is the FOCIL Framework? Solution To Reinforce Ethereum’s Impartiality

Ethereum has been fighting transaction censorship, and its co-founder, Vitalik Buterin, may have just found the solution: the FOCIL framework. But what is the FOCIL framework, and how does it solve one of Ethereum’s biggest issues?

Broadly speaking, Ethereum’s censorship risks stem from validators and MEV-boost relays that selectively exclude transactions.

Some relays, such as Flashbots, once chose to exclude transactions on Ethereum from addresses sanctioned by the Office of Foreign Assets Control (OFAC).

In fact, at its peak, over 56% of Ethereum’s blocks were OFAC-compliant.

OFAC compliant transactions

(All-Time Percentage of OFAC Compliant Transactions)

Buterin, on 22 August 2025, shared a post on X stating his plans to maintain blockchain neutrality through the Fork-Choice Enforced Inclusion (FOCIL) framework.

I think neutrality / “dumb pipe” property of the L1 is important enough that we should have multiple lines of defense to protect it:

1. Make sure that the public mempool continues to be strong and it continues to be viable to build blocks “naively”, by just grabbing txs from the…

— vitalik.eth (@VitalikButerin) August 22, 2025

In his post, he explained Ethereum’s role as a neutral Layer-1 protocol designed to process all valid transactions without bias. His comments responded to Ameen Soleimani’s concerns over the legal exposure faced by US-based Ethereum validators.

“I think neutrality/dumb pipe property of the L1 is important enough that we should have multiple lines of defence to protect it,” he said.

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What Are the Key Strategies Laid Out To Safeguard Ethereum’s Neutrality?

Buterin expanded on strategies he thinks are essential to maintain Ethereum’s neutral stance, starting with keeping the public mempool robust and ensuring it remains a reliable source of block construction without centralised filtering.

Additionally, he emphasised the importance of working on other distributed block technologies, i.e., developing new systems like the FOCIL framework or decentralised builder networks that reduce reliance on centralised block builders and relays.

Buterin proposed using ” extra inclusion channels ” to further protect against censorship, especially in scenarios where staking becomes concentrated among a few large validators.

He noted that these channels would guarantee the processing of valid transactions even if dominant validators attempt to exclude them.

Buterin explained FOCIL as a channel to expand the number of block proposers per slot from one to seventeen.

Only one of these seventeen block proposers will be able to move last and choose the transaction order, while the other sixteen will act as attestors. Further, a transaction proposed by any of the seventeen must be included in the final block, ensuring that non-privileged proposers have a much lighter weight.

He said, “They do not need to calculate the state root; they only need to compute the validation part of any transaction. They can even be stateless, so even at much higher gas limits, it’s viable for any attester to also be one of these auxiliary proposers.”

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Why Do Experts Say FOCIL Framework Will Negatively Impact US Validators?

While Buterin’s FOCIL proposal aims to solve Ethereum’s block builder oligopoly, it has also sparked legal concerns.

As he explained, FOCIL distributes transaction inclusion rights across seventeen proposers per slot, ensuring that even if two builders dominate 99% of block production, they cannot suppress valid activity.

Soleimani, however, disagrees and believes that this mechanism exposes US-based validators to serious risks.

The case against FOCIL (which I learned about today):

ETH devs, I love you. You mean well. But when you create an EIP to solve the problem of “filtering out transactions with sanctioned addresses” and your solution is “to allow validators to impose constraints on builders by… pic.twitter.com/O2FfaGO5L9

— Ameen Soleimani (@ameensol) August 22, 2025

He argued that forcing validators to include transactions from sanctioned addresses, such as those linked to Tornado Cash, could violate US sanctions law that carries penalties of up to 20 years.

Currently, validators can filter sanctioned transactions while still participating in block production.

Soleimani cautioned that FOCIL’s enforcement could make it legally impossible for US validators, as well as attestors and core system developers, to operate without risking prosecution.

Buterin, however, stood firm in his belief that Ethereum must remain a neutral protocol.

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Key Takeaways

The FOCIL framework is designed to maintain Ethereum’s transaction neutrality
FOCIL gives 17 proposers inclusion rights per slot, preventing censorship even if two builders control 99% of blocks
Valid concerns have emerged regarding FOCIL’s enforcement exposing US validators, attestors and developers to penalties

The post What is the FOCIL Framework? Solution To Reinforce Ethereum’s Impartiality appeared first on 99Bitcoins.

What is the FOCIL Framework? Solution To Reinforce Ethereum’s Impartiality