NHTSA proposes to rewrite federal brake standards to accommodate fully driverless vehicles, removing pedal requirements while preserving stopping-distance performance

Headline Finding

On 26 June 2026, the U.S. National Highway Traffic Safety Administration (NHTSA) issued a Notice of Proposed Rulemaking to update Federal Motor Vehicle Safety Standard (FMVSS) No. 135 — the federal brake standard that has governed light vehicle brake systems since 1995 — specifically to accommodate fully driverless vehicles that have no steering wheel, gas pedal, or brake pedal. The proposal does not relax any stopping-distance performance requirement; it updates the design pathway to compliance. This is a direct regulatory response to the pacing problem: existing rules written for human-driven vehicles have become an unworkable legal barrier for autonomous vehicle manufacturers seeking to certify vehicles without human-operated controls, and NHTSA is now attempting to close that gap through formal rulemaking.

Detail

FMVSS No. 135, in force since 1995, requires service brakes to be activated by a foot-operated pedal and parking brakes to be controlled by a hand or foot control. For vehicles equipped with Automated Driving Systems (ADS) — defined in the NPRM as ‘a combination of hardware and software that can perform all real-time operational and tactical functions required to operate a vehicle on a sustained basis’ — that have no manually operated driving controls, these requirements create what NHTSA describes as an ‘unworkable regulatory barrier.’ The agency notes that a brake pedal accessible to passengers in a fully autonomous vehicle could be accidentally or intentionally activated in ways that interfere with the ADS.

The most significant proposed change is that manual brake control requirements would apply only to vehicles that retain manually operated driving controls. For fully autonomous vehicles, manufacturers would have the option to remove those controls entirely. In their place, NHTSA would require on-board systems to control braking; an external-command-only system — one that could send braking signals solely from outside the vehicle — would not be permitted. NHTSA proposes a formal definition of ‘service brake control’: for human-driven vehicles, the traditional brake pedal; for ADS-equipped vehicles, the component (such as a linear actuator) that translates an electronic command from the ADS into physical braking force. The definition of ‘stopping distance’ would also be updated: for ADS-equipped vehicles, measurement would begin from the point at which the electronic braking command is transmitted, which NHTSA views as functionally equivalent to the pedal-force-application point for safety evaluation purposes.

On brake warning indicators, NHTSA proposes renaming the ‘brake system warning indicator’ to ‘brake system warning telltale’ (aligning with FMVSS No. 101), shifting the visibility requirement from ‘clear view of the driver’ to ‘clearly visible to occupan ts in all designated seating positions,’ and exempting ADS-equipped vehicles without manual controls from the requirement to activate a telltale when the parking brake is applied, since the ADS itself monitors and controls the parking brake. The agency is also seeking public comment on whether app notifications or in-vehicle alerts could serve as superior warning mechanisms.

On parking brakes, NHTSA proposes eliminating the existing friction-type specification — a legacy requirement premised on the parking brake doubling as an emergency brake — while preserving the underlying performance requirement: the parking brake must still hold the vehicle stationary for five minutes on a 20 percent grade in both directions, with engagement retained solely through mechanical means. Fully electric parking brakes that could lose holding power if power is lost would still not be permitted.

The NPRM is part of a broader 2025 Automated Vehicle Framework, which has also included NPRMs for FMVSS No. 102 (transmission shift position sequence), FMVSS Nos. 103 and 104 (windshield defrosting/defogging and wiping/washing systems), and FMVSS No. 110 (tire selection and rims). Public comments on the brake standard NPRM are due by 27 July 2026.

Governance Implication

1. LEGITIMACY lever — performance-based pathway: By preserving all stopping-distance performance requirements while updating only the design pathway to compliance, NHTSA is moving toward performance-based permitting rather than prescriptive design mandates. This is a legitimacy-positive development: it signals that federal safety standards can evolve without lowering the safety bar, which is essential for public trust in AV certification.
2. PACING PROBLEM (two clocks): The fact that a brake standard written in 1995 has remained on the books as a legal barrier to certifying vehicles already being ‘tested and deployed in limited settings’ is a textbook illustration of the governance clock lagging the technology clock. This NPRM is the governance clock attempting to catch up — but it remains a proposal, with a comment deadline of 27 July 2026, meaning the gap persists until a final rule is issued.
3. SPATIAL-ALLOCATION lever — design freedom for driverless interiors: Removing the mandatory brake pedal and hand control for fully autonomous vehicles has downstream implications for vehicle interior design and, by extension, for how ADS-equipped vehicles interact with curb space, loading zones, and passenger boarding environments. Cities designing curb management regimes should note that the federal regulatory floor is shifting to accommodate pedal-free cabins.
4. INSTRUMENT DESIGN — on-board vs. external control: The explicit prohibition on external-command-only braking systems (where braking signals could only be sent from outside the vehicle) is a meaningful safety architecture choice embedded in the proposed rule. It has implications for remote-assistance-operator frameworks and teleoperation models that cities and operators are developing in parallel.
5. CHAPTER 6 instrument gap: The NPRM is a notice of proposed rulemaking, not a final rule. Until finalized, manufacturers face regulatory uncertainty about whether pedal-free vehicles can be certified. Cities and opera tors planning ADS deployments should track the comment period and final rule timeline as a critical dependency in their permitting and procurement timelines.

Sources

https://www.crowell.com/en/insights/client-alerts/nhtsa-proposes-updates-to-federal-brake-standards-for-autonomous-vehicles-and-withdraws-av-step-program https://www.federalregister.gov/documents/2026/06/26/2026-13900/federal-motor-vehicle-safety-standards-light-vehicle-brake-systems