From Mempool to Complete Anti-Censorship Framework: How Ethereum Is Reshaping Transaction Freedom

Ethereum is undergoing a deep strategic shift. No longer limited to discussions about transaction speed or costs, the network’s core issue has shifted to a more fundamental question: When political pressure arises, key figures disappear, or certain entities are blacklisted, can Ethereum maintain its promised openness? This is not alarmism—it’s a design philosophy Vitalik Buterin has repeatedly emphasized recently.

“Technical Sanctuary”: From Abstract Value to Concrete Engineering

In early March, Vitalik proposed a new concept—positioning Ethereum as part of a “technical sanctuary” ecosystem. This sounds grand, but at its core, it’s a collection of very specific engineering challenges: How to ensure ordinary users’ transactions aren’t blocked by a few powerful actors? How to prevent transactions from being front-run before they are even included in a block?

Vitalik used a fitting analogy to explain this concept: a truly decentralized protocol should be like a hammer, not a subscription service. When you buy a hammer, it’s yours—you won’t stop working because the manufacturer goes bankrupt, nor will it suddenly display “This feature is unavailable in your region.” This kind of reliability is exactly what Ethereum needs to internalize at the protocol level.

Centralization in Block Construction and the Emergence of FOCIL

The root of the problem lies in Ethereum’s current block production process. To improve efficiency and extract MEV (Miner Extractable Value), block construction has become increasingly concentrated among a few specialized builders. In theory, any major builder can selectively review certain transactions—for example, transfers from sanctioned addresses.

FOCIL (Forced Inclusion List) is Ethereum’s direct response at the protocol level to this issue. Its mechanism involves a validator committee observing valid transactions in the mempool and forming a list that must be included. The next proposer must respect this list, and validators will only vote for blocks that comply. In other words, FOCIL doesn’t eliminate the role of builders but ensures, through consensus rules, that even if builders want to censor, they cannot bypass the network consensus.

This proposal has been scheduled for the next major Ethereum upgrade (expected in the second half of 2026). While still controversial, it is actively progressing.

The Dangers of the mempool and Encryption Solutions

However, FOCIL only addresses part of the problem. Even if a transaction is eventually included, if the entire market has already seen its contents beforehand, MEV searchers can still front-run, sandwich, or reorder transactions—especially deadly for DeFi users. Their transaction prices can be maliciously manipulated before on-chain confirmation.

That’s why mempool encryption has become another critical topic. The Ethereum Foundation researchers proposed the LUCID scheme (and related EIP-8105), which offers a possible approach:

• Users send encrypted transaction content
• Decrypt only after the transaction is included in a block and confirmed
• MEV searchers cannot see transaction intent during this period
• The public mempool becomes a trustworthy, harmless information dissemination layer

While this solution increases protocol complexity, it directly addresses a core issue: transaction visibility itself can cause harm.

The “Holy Trinity” of Censorship Resistance

Researchers have summarized a comprehensive protection scheme into three layers:

ePBS (Execution layer proposer and builder separation) prevents centralization of review power at the architecture level.

FOCIL enforces through consensus rules the inclusion of legitimate transactions.

mempool encryption protects transaction privacy, preventing front-running risks caused by intent leakage.

These three mechanisms reinforce Ethereum’s censorship resistance at different levels, forming a systemic defense framework. Notably, on February 20, Vitalik also discussed the synergistic effects of EIP-8141 (Account Abstraction upgrade) and FOCIL—indicating that censorship resistance considerations have permeated every corner of the Ethereum protocol.

From Theory to Practice: The True Meaning of the Walkaway Test

All these complex technical improvements point toward a single goal—the Walkaway Test: If all key developers disappear tomorrow, can Ethereum continue to operate normally?

This is not just a slogan. It’s a rigorous decentralization standard. It requires the protocol to not only appear decentralized today but to withstand censorship and continue serving users even in the worst-case scenarios.

When countless users can live, work, communicate, manage risks, and build wealth securely within this “digital sanctuary,” without fear of censorship or freezing by any centralized entity—then Ethereum has truly passed the Walkaway Test. This is the ultimate goal that mempool encryption, FOCIL, and the entire censorship resistance framework aim to achieve.