Ethics & The Sandwich Question

What you'll learn

• Not All MEV Is Equal
• How Sandwich Attacks Work
• MEV-Blocker, CowSwap, UniswapX
• Solana and Jito: A Different Equilibrium
• Vitalik's Endgame and Trustless Block Building

Key terms

Constructive MEV

Value capture from socially useful work — arbitrage closing price gaps, liquidations preserving lending solvency, JIT liquidity (borderline). The user is no worse off than in a no-searcher world and often better off.

Extractive MEV

Value capture that comes from harming an identifiable user. The canonical example is the sandwich attack. Pure value transfer from less-sophisticated to more-sophisticated parties without social work done.

Sandwich attack

A three-transaction MEV strategy: front-run a user's pending swap to worsen its price, let the swap execute, then back-run to capture the price impact. Solana sandwich bots earned $370-500M between January 2024 and May 2025 per Eigenphi.

MEV-Blocker

A private-RPC service launched 2023 by Cow Protocol, Beaverbuild, and others. Routes user transactions privately, prevents front-running, and refunds a share of any back-run profit. Single-digit-billions monthly volume by 2025-2026.

CoW Protocol (CowSwap)

An intent-based DEX where users sign trade intents and solvers compete in periodic batch auctions to find best execution. Eliminates per-transaction mempool exposure that enables sandwiches. Multi-billion monthly volume.

UniswapX

Uniswap Labs' intent-based protocol launched 2023. Users sign Dutch-auction orders; fillers compete to fulfill. No mempool transaction; no sandwich exposure. Uniswap's answer to the threat of intent-based protocols eating AMM volume.

Jito Block Engine

Solana's primary MEV bundle relay. Jito-Solana client runs on 70%+ of Solana stake by 2025. Tip flow exceeds $50-80M/month. Both enables sandwich attacks and offers private-flow protections; commercial incentives create tension.

Shutter Network

Threshold-cryptography-based encrypted mempool. Transactions are encrypted in the mempool and decrypted only after block inclusion is committed. Live on Gnosis Chain; Ethereum mainnet integration discussed for 2026-2027.

Inclusion list

Vitalik's proposed censorship-resistance backstop: proposers mandate inclusion of specific transactions even if builders excluded them. EIP-7547 was a 2024 candidate; refined design is on the Glamsterdam fork roadmap.

Endgame (Vitalik, 2021)

The thesis that block production will centralize because MEV economics make it economies-of-scale, but block validation will remain decentralized with protocol-level censorship-resistance backstops. The dominant conceptual frame for current MEV research.