What the Car Kill Switch Bill Actually Requires

The car kill switch bill is not actually a kill switch. It is Section 24220 of the Infrastructure Investment and Jobs Act, signed into law on November 15, 2021, and it directs federal regulators to require all new passenger vehicles to include factory-installed technology that passively detects driver impairment and prevents or limits vehicle operation when it finds it.¹ Nothing in the law lets police or anyone else shut a car off remotely. The system watches the driver, not the car, and it is aimed squarely at the 12,429 people killed by alcohol-impaired driving in 2023, roughly 30 percent of all U.S. traffic deaths.²

What Section 24220 Requires

The statute tells the Secretary of Transportation to create a new Federal Motor Vehicle Safety Standard requiring “advanced drunk and impaired driving prevention technology” in every new passenger motor vehicle. The technology must do one of two things: passively monitor the driver’s performance to identify impairment, or passively and accurately detect whether the driver’s blood alcohol concentration is above the legal limit. If it finds impairment, it has to prevent or limit vehicle operation.³

“Passively” is the key word. Unlike ignition interlock devices ordered after a DUI conviction, which force a driver to blow into a tube before the car starts, the mandated system has to work without any action from the driver. A sober person is supposed to get in and drive without noticing it exists.

The mandate covers new passenger cars, SUVs, and light trucks. It does not reach motorcycles or heavy commercial vehicles, and it does not require retrofitting anything already on the road.⁴ Because it works through the Federal Motor Vehicle Safety Standards framework, it applies to every new vehicle sold in the United States, regardless of where it was built.

How the Technology Would Detect Impairment

Two broad approaches are in development, and the eventual standard may permit either.

Sensors That Measure Alcohol Directly

The leading effort is the Driver Alcohol Detection System for Safety, or DADSS, a public-private research partnership more than 16 years in the making.⁵ DADSS uses two sensor types. A touch-based sensor built into the steering wheel or start button reads alcohol levels through the skin. A separate breath sensor samples the air inside the cabin and measures alcohol concentration without any tube to blow into.³

Cameras That Watch Driving Behavior

The second approach uses the interior cameras and sensors already appearing in many newer cars. These systems track lane drift, erratic steering, eye movement, and signs of drowsiness. Rather than measuring a chemical, they infer impairment from how badly the driver is performing.³ Several automakers already ship driver-monitoring cameras, though none yet meet the full requirements of Section 24220.

The law’s definition of impairment reaches beyond alcohol. NHTSA has said it also covers driving during an incapacitating medical emergency, so a seizure, heart attack, or diabetic episode behind the wheel falls within scope.³ Cannabis and prescription drugs are harder. There is no accepted real-time chemical threshold for marijuana impairment, and the DADSS alcohol sensors would miss it entirely. Camera-based monitoring is more promising for drug impairment because it watches behavior, but early research has flagged drowsy drivers as alcohol-impaired, and sorting fatigue from actual drug effects is still unsolved.

What Happens When the System Flags a Driver

The law says the system must “prevent or limit” vehicle operation and leaves the details to NHTSA. The response splits by timing.

If impairment is detected before the vehicle moves, the system can simply keep the engine from starting or the transmission from engaging. That is functionally close to an ignition interlock, minus the tube.

If impairment is detected while the vehicle is already at highway speed, the intervention has to be more careful. NHTSA’s rulemaking notice describes several options being researched or already shipping in some form:³

A reduced-speed mode that gradually slows the car, activates adaptive cruise control with a long following gap, and warns the driver to exit the highway.
A stop-in-lane response that slows to a halt in the current lane, activates hazard flashers, and unlocks the doors for responders.
A guided pullover that steers the vehicle to the right lane or shoulder before stopping.

Volvo has announced a Driver Understanding System in the EX90 that can brake to a standstill within the lane if the driver appears unresponsive. Mazda has demonstrated a concept designed to intervene if a driver loses consciousness. These give a preview of what the federal standard may eventually look like on the road.

NHTSA has also asked whether the final rule should include a manual emergency override, how vehicle speed should be limited if one is used, and how to keep an override from being abused routinely by impaired drivers.³ No decision has been published, but the fact that NHTSA is soliciting input suggests some form of bypass is likely.

When New Cars Will Actually Have It

Not soon. The law gave NHTSA until November 15, 2024, to issue a final rule.⁶ That deadline came and went. No proposed rule has been issued, let alone a final one.

In January 2024, NHTSA published an Advance Notice of Proposed Rulemaking, the earliest stage of the process, meant to gather information rather than propose specific requirements.³ The agency received more than 3,000 unique comments and, as of early 2026, is still working through them.⁷ In December 2025, NHTSA issued a separate request for comment on the dashboard warning indicators that would tell drivers when the system activates.⁸

The statute has a safety valve. NHTSA can extend the deadline by up to three additional years if the Secretary of Transportation determines the standard cannot yet satisfy 49 U.S.C. 30111(a) and (b), which govern the performance and objectivity of federal motor vehicle safety standards.⁶ That pushes the outer deadline for a final rule to November 2027, and automakers would still need lead time after the rule takes effect to build the technology into production vehicles. The earliest a driver is likely to encounter this system in a new car is 2029 or later.

False Positives, Privacy, and What Is Not Yet Decided

The question everyone asks first: what if the system misreads a sober driver? NHTSA is aware that a high false positive rate could sink public acceptance of the whole mandate, and its rulemaking notice explicitly asked commenters what false positive rate would place too great a burden on unimpaired drivers.³ One option the agency floated is a phased rollout that initially targets only very high blood alcohol levels, at or above 0.15 g/dL (nearly double the legal limit), before calibrating down toward 0.08 g/dL.

Privacy is the other unresolved piece. Any system that monitors a driver’s body or behavior collects sensitive data, and Section 24220 does not include specific privacy protections. NHTSA’s notice asked about reliability and durability but did not propose data retention limits, access controls, or restrictions on sharing information with law enforcement.³ Civil liberties groups have argued that the technology’s purpose is preventive rather than forensic and that the system should be built so data cannot flow to police or insurers. No federal law currently governs whether police could seek a warrant for data from an in-vehicle impairment monitor, and how courts would treat that data under the Fourth Amendment is an open question that likely will not be settled until the technology is actually deployed and challenged.

Could Congress Kill the Mandate

Possibly. Two bills in the 119th Congress push in opposite directions.

The No Kill Switches in Cars Act (H.R. 1137), introduced in February 2025, would repeal the Section 24220 requirement outright.⁹ Its supporters argue the technology creates unacceptable privacy risks and could strand sober drivers.

The Drunk Driving Prevention and Enforcement Act of 2025 (H.R. 6704) goes the other way, strengthening implementation. Its findings section notes that Congress has already directed integration of passive impaired-driving prevention technology into new passenger vehicles and that the work should move forward.¹ Its supporters point to the annual death toll from alcohol-impaired driving.

Neither bill has advanced out of committee. Even if NHTSA finalizes a rule, Congress could still repeal the underlying mandate before the compliance date arrives, so both the rulemaking at NHTSA and the legislation in Congress are worth watching.

1
Congress.gov. H.R. 6704 – Drunk Driving Prevention and Enforcement Act of 2025
2
National Highway Traffic Safety Administration. 2023 Data: Alcohol-Impaired Driving
3
Federal Register. Advanced Impaired Driving Prevention Technology
4
U.S. Congress. Public Law 117-58
5
National Highway Traffic Safety Administration. Advance Notice of Proposed Rulemaking – Advanced Impaired Driving Prevention Technology
6
National Highway Traffic Safety Administration. 2024 Report to Congress – Advanced Impaired Driving Prevention Technology
7
National Highway Traffic Safety Administration. Report to Congress – Advanced Impaired Driving Prevention Technology
8
Regulations.gov. NHTSA Notice and Request for Comment – Advanced Drunk Driving Prevention Technology Telltale Development
9
Congress.gov. H.R. 1137 – 119th Congress (2025-2026) – No Kill Switches in Cars Act