Ethereum’s founder, Vitalik Buterin, has proposed several measures to protect the decentralization of the blockchain of the world’s second-largest cryptocurrency by market capitalization. He emphasized the importance of maintaining “naive” block construction through a public mempool.
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
The programmer outlined three key areas to prevent centralization and maintain Ethereum’s openness, even if block creation falls under the control of major players. He highlighted:
- strengthening the public mempool;
- developing distributed block-building technologies outside the protocol;
- adding additional channels for transaction inclusion.
One such channel is the FOCIL mechanism, which will prevent transaction censorship. It involves selecting 17 validators for each slot, one of whom will determine the final order of operations in the block.
“The work of the 16 ‘non-privileged’ validators (who merely select transactions for inclusion in the block) will become much easier: they will not need to perform complex computations—basic validation of operations will suffice,” Buterin noted.
According to him, any network participant can become an auxiliary validator, supporting decentralization.
“With full account abstraction (for example, EIP-7701), this mechanism can be extended to transactions of smart contract wallets, withdrawals from private protocols, and so on, allowing them to operate without reliance on centralized intermediaries,” added the Ethereum founder.
Not So Simple
Buterin responded to a tweet from Ethereum developer Amin Soleimani, who expressed concerns about implementing FOCIL. He warned that it could pose significant issues for U.S. validators. Forcing the inclusion of transactions from sanctioned addresses would deprive network participants of the right to filter them, potentially leading to legal consequences.
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
As an example, the programmer cited Tornado Cash. At the height of the authorities’ investigations into the crypto mixer developers, 90% of nodes in the Ethereum network filtered operations related to the service, merely increasing processing time from 15 to 150 seconds. FOCIL could disrupt this model.
Soleimani noted that the U.S. government might ignore Buterin’s outlined scheme and prosecute validators for including prohibited operations.
“There is a possibility that FOCIL will lead to legal liability for the main developers who designed and implemented it, as it was clearly created to prevent validators from filtering transactions with sanctioned addresses,” he concluded.
Many developers sided with Buterin. According to a user with the nickname tim-clancy.eth, the FOCIL mechanism is “critically important for scaling” Ethereum.
FOCIL is the single most important EIP for Ethereum. It should have shipped years ago and it delivers a capability that Ethereum _must_ have to continue delivering on its mission of being the most neutral blockspace. FOCIL does nothing to the application layer: you can apply…
— tim-clancy.eth (@_Enoch) August 22, 2025
“FOCIL is the most important EIP for Ethereum. It should have been implemented years ago; it provides a capability necessary for the network to maintain its mission of being the most neutral blockchain space,” he wrote.
Earlier in August, Buterin identified Ethereum’s key goal for the next decade as ensuring the network’s seamless operation to preserve users’ digital autonomy.