JIP-4: Authorization to Blacklist Validators for Mempool Participation

1. Authorization to Blacklist Validators for Mempool Participation

2. Abstract

This Jito Improvement Proposal (JIP) seeks to empower a working group of validators and community members to enforce a one-time blacklist of validators from the Jito Stake Pool who have been found to be engaged in behaviors deemed harmful to the Solana ecosystem, such as private mempool participation.

This working group will be responsible for a one-time vote only. A future Solana ecosystem-wide committee is currently being formed to construct future blacklists, and the DAO will debate how to utilize this committee’s data in the future.

3. Motivation

An investigation conducted by Jito Labs recently found that roughly ~10% of Jito Stake Pool validators are currently engaged in private mempool participation. The results of this investigation have been shared among ecosystem partners, including the Solana Foundation Delegation Program, leading to their recent blacklisting action.

The motivation behind this proposal is to gather a group of Jito delegates, empower them to review the investigation’s evidence, and allow them to make a determination as to whether Jito Labs should enforce the blacklist.

4. Key Terms

  • Solana: Solana is a credibly neutral blockchain.
  • Jito Foundation: The Jito Foundation is an opinionated legal entity whose mandate includes promoting productive adoption of Jito Network products as well as the broader Solana ecosystem.
  • Blacklist: A list of validators prohibited from receiving stake from JitoSOL network due to harmful behaviors.
  • Private Mempool: Non-public mempools in which transactions are broadcast to searchers ahead of finality, providing an opportunity for searchers to execute harmful MEV strategies such as sandwich attacks.
  • Working Group: A group of Jito delegates and community members responsible for reviewing evidence from Jito Labs and making the decision whether or not to enforce a one-time blacklist.

5. Specification

Working Group Formation

  • This proposal will lead to the establishment of a working group of 4 respected Solana validators and two non-validator overseers, prioritizing current governance delegates from the validator community, selected by the Jito Foundation.
  • The working group will be responsible for reviewing evidence from the Jito Labs investigation and deciding on whether or not to enforce a blacklist.
  • The working group members would include:
    • Michael Hubbard - Stakewiz (Validator)
    • OxNallok - Lode Ventures (Validator)
    • Chris Remus(x.com) - Chainflow (Validator)
    • Ben - mrgn (Validator + Solana core contributor)
    • Blockworks Research (Non-validator representative)
    • Mark - Kamino (Non-validator representative)

Blacklist Criteria

Jito Labs’ recent investigation found a number of Solana-wide validators participating in private mempools, including members of the Jito Stake Pool.

To ensure the efficacy of future investigations, the investigative process will have to remain confidential, aside from being shared with the blacklist committee who will be trusted to make a determination about its validity.

If the committee finds the investigation to be valid, they will recommend that Jito Labs enforce the blacklist.

A list of validators who would be affected if the committee finds the investigation to be valid includes: Data

6. Benefits/Risks


  • Enhanced Network Integrity: Reducing harmful behaviors will improve the overall health, performance and decentralization of the Solana network.
  • Fair Rewards Distribution: Ensuring all validators play by the same rules will promote a fair distribution of rewards.


  • Centralization Risk: Because the detection methods have to remain private by nature, this one-time blacklist committee participation entails a high-trust position.
  • Conflict of Interest: Members of the working group may face backlash from blacklisted validators/their colleagues in the community.

7. Outcomes

Successful implementation of this proposal will result in the establishment of a committee to review evidence and determine whether Jito Labs should enforce a one-time blacklist.

A future proposal will consider how to manage investigations from a forthcoming ecosystem-wide committee in the future.

8. Cost Summary

The implementation of this proposal will initially require no financial resources from the DAO.

Note: this proposal has been heavily edited from its draft version in order to focus solely on a one-time enforcement committee. A future proposal will cover how the DAO will manage the blacklist going forward.


Thanks for this proposal Andrew.

This is a very sensitive and important topic and a key point in the evolution of the Jito stake pool and for the network as a whole as it grapples with social enforcement of norms.

I look forward to participating in the working group to ensure there is a full understanding of the investigation’s methodology, it’s risks of type I and II errors and resulting confidence of detection for each identified validator, and will only recommend blacklisting where there is sufficiently high confidence on my part as well as sufficient consensus within the working group.

I appreciate that this is a one-time instance with a view of a longer-term collaborative effort across ecosystem teams as we figure out how to approach the situation in the best, fairest and most sustainable way.


Hi there!

It’s great to see this initiative, is good for protocol health.

My understanding is that this is a one time instance. How will you avoid other “malicious” validators to join the pool in the future? Is the provided validators list final?

What’s the implementation timeline if passed?

We agree with JIP-4 on the premise that it aligns Jito Governance with its network while prioritizing Solana users. However, we approach this proposal with caution, as censorship can often begin with good intentions. Jito currently controls a sizable portion of the LST market, acting as a proxy to the network at large. Despite our concerns, we believe that this JIP will help distinguish Jito in the long run by demonstrating the protocol’s dedication to preserving user experience. This may encourage other players in the ecosystem to adopt similar prohibitions against blacklisting, thereby creating early social enforcement against malicious activity.

Finally, we would like to request the establishment of a Constitution or set of rules that clearly defines what Jito considers violations of the protocol in the future. The Constitution could possibly be amended or changed given a governance process much later. This would provide guidelines for actions that result in blacklisting, ensuring every participant understands what constitutes a blacklist-able offense.

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