NHTSA Proposes Updates to Federal Brake Standards for Autonomous Vehicles and Withdraws AV STEP Program

On June 26, 2026, the National Highway Traffic Safety Administration (NHTSA) took two major actions related to autonomous vehicles. First, NHTSA issued a Notice of Proposed Rulemaking (NPRM) proposing significant updates to Federal Motor Vehicle Safety Standard (FMVSS) No. 135, which has governed light vehicle brake systems in passenger cars and light trucks since 1995.^[1]  Second, NHTSA formally withdrew its January 15, 2026 NPRM, which had proposed the Automated Driving System-Equipped Vehicle Safety, Transparency, and Evaluation Program (AV STEP), a voluntary program for vehicle manufacturers, fleet operators, and system integrators of autonomous vehicles and automated driving systems.

Key Changes Proposed to FMVSS No. 135

The proposed changes to FMVSS No. 135 are driven by the central reality that autonomous vehicles generally do not have steering wheels or brake pedals, and the existing regulations were not written with that in mind. The agency seeks comments on its proposed rule by July 27, 2026. The key proposed changes are summarized below.

FMVSS No. 135 currently requires that service brakes be activated by a foot-operated pedal and that parking brakes be controlled by a hand or foot control. For vehicles equipped with Automated Driving Systems (ADS)^[2]  that have no manually operated driving controls — meaning no steering wheel, no gas pedal, and no brake pedal — these requirements create an unworkable regulatory barrier.

ADS-equipped vehicles are already being tested and deployed in limited settings, and manufacturers need a clear legal pathway to certify these vehicles without being forced to include human-operated controls that are unnecessary and, in some cases, potentially unsafe. A brake pedal accessible to passengers in a fully autonomous vehicle could, for instance, be accidentally or intentionally activated in ways that interfere with the ADS.

What NHTSA is Proposing to Change in FMVSS No. 135

The most significant change is that manual brake control requirements, the foot pedal for the service brake and the hand or foot control for the parking brake, would only apply to vehicles that have manually operated driving controls. For fully autonomous vehicles with no human driver, manufacturers would have the option to remove those controls.

In their place, NHTSA would require that on-board systems control braking in autonomous vehicles. An external command system that could only send braking signals from outside the vehicle would not be permitted. The core safety obligation remains, regardless of how the brakes are activated, every vehicle must still meet the existing stopping distance performance requirements. That does not change.

NHTSA proposes adding a formal definition of “service brake control.” For vehicles with a driver, this means the traditional brake pedal. For autonomous vehicles, it refers to 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 vehicles with a pedal, it continues to measure from the point of physical force application. For ADS-equipped vehicles, it measures from the point at which the electronic braking command is transmitted. NHTSA views both as functionally equivalent for safety evaluation purposes.

NHTSA proposes multiple changes related to the brake system warning telltale:

• First, NHTSA proposes to rename the “brake system warning indicator” to “brake system warning telltale,” aligning the terminology with FMVSS No. 101, which governs controls and displays.
• Currently, the warning telltale must be in clear view of the driver. Since fully autonomous vehicles have no driver, only passengers, NHTSA proposes that the telltale instead be clearly visible to occupants in all designated seating positions.
• NHTSA also proposes to exempt ADS-equipped vehicles without manually operated driving controls from the requirement to activate a telltale when the parking brake is applied, since the ADS itself monitors and controls the parking brake as part of normal operations.
• NHTSA is exploring whether alternative methods such as app notifications or in-vehicle alerts could serve as superior ways to communicate safety warnings to passengers, and is seeking public comment on this question.

FMVSS No. 135 currently requires parking brakes to be of the friction type — a requirement carried over from an older standard based on the premise that the parking brake might need to double as an emergency brake if the primary system fails. NHTSA now proposes to eliminate this friction-type specification, recognizing that modern vehicle technology has rendered it unnecessary. Critically, the underlying performance requirement remains intact: the parking brake must still be capable of holding the vehicle stationary for five minutes on a 20 percent grade in both directions, and engagement must be retained solely through mechanical means. Fully electric parking brakes, which could lose holding power if power is lost, would still not be permitted.

What NHTSA is Not Changing in FMVSS No. 135

NHTSA is clear that it is not proposing any changes to stopping distance requirements. All vehicles, whether driven by a human or an ADS, must demonstrate the same braking performance. Safety performance standards are not being relaxed— only the design pathway to achieve compliance is being updated. For vehicles and fleets operating or developing ADS technology, this proposed rule represents a meaningful step toward a regulatory framework that keeps pace with the technology while preserving the underlying safety performance standards.

NHTSA is accepting public comments through July 27, 2026. The agency is particularly interested in comments on the proposed removal of manual brake control requirements, the definitions of service brake control and stopping distance, telltale visibility options for ADS-equipped vehicles, and the elimination of the friction-type parking brake requirement.

Crowell will continue to monitor this issue and is available to assist in assessing potential compliance obligations and formulating comment submissions.

NHTSA’s Withdrawal of the AV STEP Program

NHTSA formally withdrew its prior NPRM, proposing the AV STEP program. This AV STEP program would have imposed reporting and public disclosure requirements on participating entities in exchange for potential exemptions to FMVSS requirements. The June 26, 2026, notice of withdrawal can be found here.

Overall, NHTSA’s stated rationale for withdrawing AV STEP included that a “key intention of the proposal was to establish a regulatory program that resulted in NHTSA overseeing a substantial volume of ADS operations,” but the response from industry stakeholders indicated participation would have been “minimal.” For example, the Alliance for Automotive Innovation warned “there is a high likelihood that for most potential applicants, the burdens of the current reporting requirements would outweigh the benefit of program participation.”

Similarly, the ACES Mobility Coalition suggested the AV STEP program “introduces unnecessary reporting burdens and new operational restrictions, without providing any meaningful regulatory or safety benefits.” And other safety organizations such as the National Safety Council (NSC) commented that the program should be shifted from “voluntary to mandatory,” because “[n]ovel, ‘unproven’’ technology should not be able to operate on public roads where operating conditions are not predictable…”

NHTSA also raised that there was a significant disagreement on whether AV STEP appropriately balanced federal regulation against potentially overlapping state and local requirements– some industry stakeholders lobbied for a uniform federal program, but others supported a state-by-state oversight structure. Moreover, stakeholders had raised concerns with an “essential element” of the program, the independent assessor concept for determining the safety of new proposed autonomous vehicle standards and designs. Because the intent of the program was to be voluntary, and in light of these comments, NHTSA concluded that there would be “sparse participation” in AV STEP.

Though AV STEP has been withdrawn, NHTSA emphasized that the goals of the AV STEP program, such as “removing unnecessary regulatory barriers” to the progress of autonomous vehicles, were still being met in other ways. As examples of this progress, NHTSA cited to the April 2025 expansion of the Automated Vehicle Exemption Program, the “streamlined” General Exemption process under 49 U.S.C. 30113 announced by NHTSA’s chief counsel in June 2025, and the “streamlined” standing General Order on Crash Reporting which focuses on “critical safety information while removing duplicative requirements.”

More information on this “AV Framework” and these prior changes can be found here.