Cardano’s technical steering committee disclosed a proposal to allow an expedited shutdown of the upcoming Leios scaling path during severe network incidents. The measure, detailed in Cardano Amendment Proposal 12 (CAP‑12), would let the network set the endorser‑block transaction size to zero, effectively disabling Leios while preserving ordinary block production. The proposal, submitted on Nov. 6 by governance participant Kevin Hammond, aims to provide a safety valve without bypassing the standard voting and enactment steps required for protocol changes.

Fast‑track governance mechanism

According to CryptoSlate, the fast‑path would waive the PARAM‑04a notice requirement for Severity 1 or 2 issues, permitting the zero‑value setting in any epoch. Re‑enabling Leios would still follow the normal governance process, including stake‑pool operator votes and Constitutional Committee approval. Hammond emphasized that the switch‑off must be confirmed in writing by the Linear Leios team and that node implementations must interpret a zero value consistently, matching the existing Praos block‑production model.

Development status of Leios

NewsBTC’s weekly report notes that Leios remains in a research and prototype phase, with recent work on endorser‑block production, certificate checks, and adaptive endorsement sizing (rc‑2026w44). The update highlighted performance improvements, such as reducing certifying‑block forging time from 0.9 seconds to milliseconds, but clarified these are internal metrics, not user‑visible transaction speeds. Additional changes include memory‑use reductions in the ouroboros‑consensus library and parallel scaling efforts by Hydra and the Plutus teams.

Implications and next steps

If adopted, the emergency shutdown route would reconcile a constitutional ban on zero‑valued Leios parameters with a conditional exception, requiring test‑net exercises on Preview and Preprod networks to verify behavior against the Praos baseline. The Parameter Committee has yet to review the specific numerical values, and the broader constitutional amendment is expected to be submitted by Nov. 25. Meanwhile, the Leios prototype is not slated for mainnet deployment, and Cardano’s scaling roadmap continues to depend on successful integration testing and stakeholder consensus.

What to watch next

Stakeholder feedback on CAP‑12 during the upcoming Nov. 18 review, test‑net results confirming zero‑parameter handling, and the timeline for the combined node 11.3 release candidate are key indicators of progress. Observers should also monitor Hydra and Plutus updates, as they complement Leios in Cardano’s broader scaling strategy. Finally, any formal amendment to the constitution that reconciles the zero‑value exception will signal whether the fast‑track shutdown mechanism can become operational.