Sequencers are centralized bottlenecks. An L2's sequencer can censor or reorder user transactions, replicating the exact permissioned control that blockchains were built to eliminate.
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Why Forced Inclusion Is a Non-Negotiable Feature for Any L2
An analysis of forced inclusion as the critical technical mechanism that prevents total sequencer censorship, preserving the cypherpunk ethos of user sovereignty in modern L2 design.
introduction
THE ARCHITECTURAL FLAW
Introduction: The Centralization Trap
The lack of forced transaction inclusion creates a single, sequencer-controlled point of failure that undermines L2 decentralization.
Forced inclusion is the escape hatch. This feature allows users to bypass the sequencer by submitting transactions directly to the L1 contract, guaranteeing finality and breaking the censorship monopoly.
The standard is Arbitrum and Optimism. Both major rollups implement forced inclusion, setting the baseline for credible neutrality. Networks without it, like many early optimistic or ZK rollups, delegate ultimate control to a single entity.
Evidence: The mempool is sovereign. Forced inclusion leverages the Ethereum base layer as a decentralized mempool, a concept validated by protocols like Flashbots' SUAVE which aim to decentralize block building itself.
key-insights
THE L2 IMPERATIVE
Executive Summary
Forced inclusion is the cryptographic guarantee that prevents L2s from becoming extractive, censored toll roads.
01
The Problem: Censorship as a Service
Without forced inclusion, a sequencer can arbitrarily block transactions, turning the L2 into a permissioned system. This violates the credibly neutral promise of Ethereum.
- Arbitrum and Optimism have this power today, relying on social consensus.
- A malicious or compliant sequencer could freeze $10B+ TVL.
- Creates regulatory single points of failure.
1
Single Point
$10B+
At Risk
02
The Solution: Ethereum as the Ultimate Arbiter
Forced inclusion allows users to submit transactions directly to the L1 contract, bypassing a censoring sequencer. The L1 forces the L2 to include it.
- zkSync and Starknet implement this via L1-L2 messaging.
- Final backstop ensures liveness and credible neutrality.
- User pays L1 gas, but transaction is executed on L2.
L1 Gas
Cost Floor
100%
Uptime
03
The Consequence: Eliminating MEV Cartels
A sequencer with exclusive ordering rights is a centralized MEV extraction engine. Forced inclusion breaks this monopoly.
- Enables permissionless MEV-Boost-like markets for L2 block building.
- Flashbots SUAVE and CowSwap-style intents can compete on L2.
- Drives transaction costs toward pure marginal cost, not rent extraction.
-50%
Rent Extraction
Permissionless
Competition
04
The Benchmark: How Starknet & zkSync Do It
These ZK-Rollups implement forced inclusion via verifiable delay functions and priority queues on L1.
- Starknet: Message queue on L1 with a ~5 day escape hatch delay.
- zkSync Era: L1
requestL2Transactionfunction with priority fee. - Both prove that technical complexity is solvable; it's a design choice.
~5 days
Max Delay
ZK-Proof
Enforcement
05
The Trade-off: Latency vs. Guarantees
Forced inclusion is a safety net, not a primary path. It trades slower finality for absolute security.
- Primary path: ~2s latency via sequencer.
- Fallback path: ~10 min to days via L1, costing ~$50-200 in gas.
- This explicit trade-off is superior to hidden centralization.
~2s
Fast Path
~$200
Escape Cost
06
The Verdict: A Litmus Test for Validiums
For Validiums (like Immutable X), forced inclusion is impossible without data availability on-chain. This creates a fundamental security vs. scalability choice.
- Validiums rely 100% on the Data Availability Committee's liveness.
- Celestia or EigenDA can decentralize DA but don't solve forced inclusion.
- Forces a clear categorization: Rollup (with escape hatch) vs. Validium (without).
0
Forced Inclusion
Committee
Trust Assumption
thesis-statement
THE NON-NEGOTIABLE
The Core Argument: Sovereignty is Binary
Forced inclusion is the definitive technical mechanism that separates a sovereign L2 from a glorified sidechain.
Sovereignty is binary: An L2 either has forced inclusion or it does not. This is the technical definition of sovereignty, not a marketing term. Without it, the L1 cannot compel transaction execution, making the L2's security optional and its state finality subjective.
Forced inclusion is the kill switch: It allows users to bypass a malicious sequencer by submitting transactions directly to the L1. This is the ultimate credible threat that ensures the sequencer behaves, making protocols like Arbitrum and Optimism credibly neutral.
Compare to sidechains: A sidechain like Polygon PoS lacks this mechanism. Its validators have absolute, unassailable control over transaction ordering and censorship. Users have no recourse but to trust the operator, which is the antithesis of Ethereum's trust-minimized ethos.
Evidence: The Ethereum roadmap explicitly defines rollups by their ability to force inclusion via L1. This is why EigenDA and Celestia as standalone DA layers create 'sovereign' rollups that are, by this definition, not Ethereum L2s but appchains with different security properties.
deep-dive
THE L1 ESCAPE HATCH
How Forced Inclusion Works: The Technical Bulwark
Forced inclusion is the mechanism that guarantees an L2 user can always publish their transaction directly to the underlying L1, bypassing any sequencer censorship.
Forced inclusion is a liveness guarantee. It is the final, non-censorable path for a transaction to reach the L1, ensuring the sequencer cannot become a centralized point of failure. This transforms the sequencer from a trusted operator into a performance-optimizing service.
The mechanism functions as an L1 contract. Users submit transactions directly to a permissionless inbox contract on Ethereum, like Arbitrum's Delayed Inbox or Optimism's L1CrossDomainMessenger. This contract enforces a delay, then forces the L2 to process the transaction in its next state update.
This delay is the economic trade-off. The forced inclusion path is slower and more expensive than the sequencer's fast lane, creating a market for liveness. Users pay for speed and subsidized gas with the sequencer, or pay for censorship resistance via L1.
Evidence: Without it, withdrawals fail. If a malicious sequencer censors a user's withdrawal, forced inclusion is the only recourse. Protocols like Across and Hop rely on this property for their bridge security models, as it guarantees message delivery.
CENSORSHIP-RESISTANCE AUDIT
L2 Forced Inclusion Implementation Matrix
A comparison of how major L2s implement the non-negotiable feature of forced inclusion, which guarantees users can exit to L1 even if the sequencer is malicious or censoring.
| Core Mechanism | Arbitrum (via AnyTrust) | Optimism (via Fault Proofs) | zkSync Era (via L1→L2 Txs) | Starknet (via L1→L2 Messages) |
|---|---|---|---|---|
Primary Forced Tx Path | Submit to L1 Delayed Inbox | Publish to L1 Output Root & Challenge | Post L1 Transaction with maxFeePerGas | Send L1→L2 Message with Fee |
Time to Force Inclusion (Est.) | ~24 hours (DAC fallback) | ~7 days (Dispute window) | ~1 hour (L1 block time) | ~1 hour (L1 block time) |
User Action Required | Call | Initiate fraud proof challenge as validator | Submit L1 tx with zkSync contract | Submit L1 tx with Starknet core contract |
Cost to User (Gas Est.) | ~200k-500k gas (L1 calldata) |
| ~150k-300k gas (L1 execution) | ~200k-400k gas (L1 execution) |
Relies on Active External Validators | ||||
Requires Full Node Sync | ||||
Formalized in Protocol Spec | ||||
Live on Mainnet |
counter-argument
THE COST OF COMPROMISE
The Steelman: "It's Too Expensive and Clunky"
Forced inclusion is the only mechanism that guarantees L2 users a reliable, sovereign exit to Ethereum.
Forced inclusion is non-negotiable because it is the ultimate user escape hatch. Without it, a sequencer can censor a withdrawal transaction indefinitely, trapping user funds. This is a fundamental security failure that no amount of sequencer decentralization or fraud proofs can fully mitigate.
The cost argument is a red herring. The gas for a forced inclusion transaction is a one-time, user-paid insurance premium. This is cheaper than the systemic risk of relying on bridges like Across or Stargate as a primary exit, which introduces new trust assumptions and smart contract risk.
Compare to a rollup without it. An L2 lacking forced inclusion is not a true rollup; it is a validium or optimistic chain. This distinction is critical for institutional adoption, where legal and regulatory frameworks require unambiguous finality guarantees on the base layer.
Evidence: The Arbitrum and Optimism mainnets both implement forced inclusion. Their sequencers have processed millions of forced transactions without systemic congestion, proving the mechanism's operational viability and low overhead.
risk-analysis
WHY FORCED INCLUSION IS NON-NEGOTIABLE
The Slippery Slope of Compromise
Without a mechanism to force transactions onto the L1, L2s cede ultimate sovereignty to their sequencers, creating systemic risk.
01
The Censorship Attack Vector
A centralized sequencer can block transactions, turning the L2 into a permissioned system. This defeats the core value proposition of decentralized finance.
- Risk: State-level actors or malicious operators can blacklist addresses.
- Precedent: The OFAC compliance of Tornado Cash transactions highlights this pressure point.
- Outcome: Without forced inclusion, users have no recourse, breaking the credible neutrality of the chain.
100%
User Recourse
0
Tolerance
02
The Liveness Guarantee
Forced inclusion acts as an escape hatch, guaranteeing transaction finality even if the sequencer fails or goes offline.
- Mechanism: Users can submit transactions directly to the L1 bridge/rollup contract.
- Analogy: It's the L2 equivalent of Ethereum's txpool; a decentralized backstop.
- Critical For: Wallets, bridges (like Across, LayerZero), and arbitrage bots that must operate under all conditions.
~15 min
Max Delay
100%
Uptime
03
The Economic Capture Problem
Sequencer profits from MEV and transaction ordering. Without forced inclusion, they have a monopoly and can extract maximum value from users.
- Result: Higher effective costs and predatory front-running.
- Contrast: Protocols with enforced inclusion (conceptually like CowSwap's solver competition) create a more equitable fee market.
- Long-term: A captured sequencer stifles innovation and application-specific rollup (appchain) viability.
-90%
MEV Extractable
1
Monopoly Breaker
04
Arbitrum's Security Council vs. Pure Code
Relying on a multisig or council for emergency inclusions adds governance risk and delays. Forced inclusion via smart contract is superior.
- Weakness: Councils can be slow, corrupted, or politically deadlocked.
- Strength: Code-based forced inclusion is deterministic, permissionless, and instant upon L1 confirmation.
- Verdict: Optimism's fault proofs and inclusion are a step forward, but the gold standard is a trustless, automatic path.
~7 days
Gov Delay Risk
~1 block
Code Speed
05
The Interoperability Requirement
Cross-chain messaging and bridging protocols require guaranteed inclusion to settle disputes and complete withdrawals. Without it, the entire interoperability stack is fragile.
- Dependency: LayerZero, Wormhole, and Hyperlane's optimistic verification models need this guarantee.
- Failure Mode: A sequencer can censor a critical fraud proof or withdrawal, freezing billions in bridged assets.
- Systemic Risk: Compromises L2's role as a secure settlement layer for the broader multi-chain ecosystem.
$10B+
TVL at Risk
1
Critical Path
06
The Slippery Slope Itself
Compromising on forced inclusion is the first step toward re-creating the traditional financial system with extra steps. It's a foundational property, not a nice-to-have.
- Historical Parallel: Allowing small compromises on decentralization (Ethereum's DAO fork, Ripple vs. SEC) leads to existential redefinition.
- Architectural Truth: If you can't force your transaction, you don't own your assets. Period.
- Non-Negotiable: This is the line between a scaling solution and a glorified database.
0
Compromises
1st
Principle
takeaways
FORCED INCLUSION
The Non-Negotiables: A Builder's Checklist
Forced inclusion is the cryptographic guarantee that valid transactions cannot be censored by a sequencer, making it a foundational security primitive for any credible L2.
01
The Censorship Attack Surface
Without forced inclusion, a malicious or compliant sequencer can blacklist addresses, creating systemic risk. This undermines the core value proposition of a credibly neutral settlement layer.
- MEV Extraction: Sequencers can front-run or censor transactions for profit.
- Regulatory Capture: A single point of failure for legal pressure, unlike Ethereum's permissionless validator set.
- Protocol Failure: Critical functions like governance or liquidations can be halted, threatening $10B+ TVL.
1
Single Point of Failure
$10B+
TVL at Risk
02
The Escape Hatch: Direct L1 Submission
Forced inclusion is implemented via a permissionless L1 contract that accepts proofs for censored transactions. This is the canonical solution, as seen in Optimism and Arbitrum.
- Guaranteed Liveness: Users can force-tx inclusion with a ~1-week delay, breaking sequencer monopoly.
- Cost as Deterrent: The high L1 gas cost discourages frivolous use but ensures availability.
- Sovereignty: Aligns with Ethereum's trust model, making the L2 a true extension, not a walled garden.
~1 Week
Max Delay
100%
Uptime Guarantee
03
Why 'Social Consensus' Fails
Promises of "good behavior" or multi-sig interventions are not a substitute for cryptographic force. This is the critical lesson from dYdX v3 (centralized sequencer) vs. its v4 fork.
- Not Credibly Neutral: Relies on trusted actors, introducing legal and counterparty risk.
- Slow Response: Manual intervention is too slow for ~500ms DeFi arbitrage or liquidation events.
- Precedent: Sets a bad standard where user rights are optional, not guaranteed by code.
~500ms
Arb Window
0
Cryptographic Guarantees
04
The Builder's Litmus Test
Evaluating an L2's forced inclusion mechanism is a first-principles check for long-term viability. Ask: Can a user today force-include a tx if the sequencer disappears?
- Implementation Check: Is there a live, audited L1 contract? (e.g., Optimism's L1CrossDomainMessenger).
- Cost Reality: Are force-inclusion fees reasonable, or are they priced as a punitive deterrent?
- Adoption Signal: Its absence is a red flag for projects prioritizing growth over credibly neutral infrastructure.
1
Critical Question
Red Flag
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