I do this for a living, let's sort this out....law is here, starting on page 403.

Section 24220, here we go:

SEC. 24220. ADVANCED IMPAIRED DRIVING TECHNOLOGY.

yada yada yada...bullshit legal-speak, definitions...yada yada...

(1) ADVANCED DRUNK AND IMPAIRED DRIVING PREVENTION TECHNOLOGY.—The term ‘‘advanced drunk and impaired driving prevention technology’’ means a system that—

(A) can—

(i) passively monitor the performance of a driver of a motor vehicle to accurately identify whether that driver may be impaired; and

(ii) prevent or limit motor vehicle operation if an impairment is detected;

(B) can— (i) passively and accurately detect whether the blood alcohol concentration of a driver of a motor vehicle is equal to or greater than the blood alcohol concentration described in section 163(a) of title 23, United States Code; and

(ii) prevent or limit motor vehicle operation if a blood alcohol concentration above the legal limit is detected; or

( C) is a combination of systems described in subpara- graphs (A) and (B).

So far, not a kill switch, but some kind of technology to detect if you're driving like a drunk person and disable the vehicle. Not really ideal, I personally don't know if technology like this currently exists, if false positives would be a problem etc. Let's continue

( c) ADVANCED DRUNK AND IMPAIRED DRIVING PREVENTION TECHNOLOGY SAFETY STANDARD.—Subject to subsection (e) and not later than 3 years after the date of enactment of this Act, the Secretary shall issue a final rule prescribing a Federal motor vehicle safety standard under section 30111 of title 49, United States Code, that requires passenger motor vehicles manufactured after the effective date of that standard to be equipped with advanced drunk and impaired driving prevention technology.

(d) REQUIREMENT.—To allow sufficient time for manufacturer compliance, the compliance date of the rule issued under subsection ( c) shall be not earlier than 2 years and not more than 3 years after the date on which that rule is issued.

OOF, Congress is mandating a new FMVSS. And with only 3 years to do it. This is impossible. NHTSA (National Highway Safety and Traffic Administratiion) doesn't do anything...I was about to write "quickly", but a better term would be "not slow". So, for NHTSA to issue a new FMVSS, here is a thumbnail sketch of the process:

0. I'm numbering this "0" because it will be entirely behind the scenes, and I don't have any idea how much time it will take. Theoretically, NHTSA could already have a team working on this, but I doubt it. NHTSA will hold focus groups, industry meetings, etc. requesting input on how they can deal with this mandate from Congress.

1. NHTSA proposes a new Safety Standard. Someone writes a draft, and this is published to give the public a chance to read it (in the Federal Register, hereon FR). Most of what they publish will be page after page after page of justifications for what Congress has mandated, some of it will be an overview of what they've found from the meetings they've held, and a little of it will be the actual text of the draft. The will also request comments, and open a docket (https://www.regulations.gov) where they will publish the comments. Usually there's a limit of 90 days on comments.

2. The comment time limit will get very close to expiring, and someone from the Automotive Industry will request an extension. NHTSA will extend for another 60 days.

3. Time will pass. More time will pass. You will forget this was ever an issue, because you have other things to deal with. I won't forget though, because every once in a while I go to the docket to read absolute batshit anonymous comments from the public (yes, you can comment anonymously.)

4. Out of the blue, NHTSA will publish another notice in the Federal Register. This one will be page after page after page of analysis from the public comments. They won't mention any from the actual public, just the ones from the major car manufacturers and industry lobbying groups. They will also either publish the Final Rule (and give a time limit for implementation), or say they are scrapping the entire thing and going back to the drawing board.

(e) TIMING.—If the Secretary determines that the Federal motor vehicle safety standard required under subsection ( c) cannot meet the requirements and considerations described in subsections (a) and (b) of section 30111 of title 49, United States Code, by the applicable date, the Secretary—

(1) may extend the time period to such date as the Sec- retary determines to be necessary, but not later than the date that is 3 years after the date described in subsection ( c);

(2) shall, not later than the date described in subsection ( c) and not less frequently than annually thereafter until the date on which the rule under that subsection is issued, submit to the Committee on Commerce, Science, and Transportation of the Senate and the Committee on Energy and Commerce of the House of Representatives a report describing, as of the date of submission of the report—

(A) the reasons for not prescribing a Federal motor vehicle safety standard under section 30111 of title 49, United States Code, that requires advanced drunk and impaired driving prevention technology in all new pas- senger motor vehicles;

(B) the deployment of advanced drunk and impaired driving prevention technology in vehicles;

( C) any information relating to the ability of vehicle manufacturers to include advanced drunk and impaired driving prevention technology in new passenger motor vehicles; and

(D) an anticipated timeline for prescribing the Federal motor vehicle safety standard described in subsection (c); and

(3) if the Federal motor vehicle safety standard required by subsection ( c) has not been finalized by the date that is 10 years after the date of enactment of this Act, shall submit to the Committee on Commerce, Science, and Transportation of the Senate and the Committee on Energy and Commerce of the House of Representative a report describing—

(A) the reasons why the Federal motor vehicle safety standard has not been finalized;

(B) the barriers to finalizing the Federal motor vehicle safety standard; and

( C) recommendations to Congress to facilitate the Fed- eral motor vehicle safety standard.

Okay, here it is. The time limit for this new rule is actually 6 years, but what Congress has really mandated is that NHTSA submit a report to them in 10 years on why they can't implement a Safety Standard on how to implement a (passive) way to disable a vehicle due to an impaired driver.

One thing that NHTSA is very good at is using "vehicle safety" as a reason not to do something. For example, Europe and Canada already have regulations requiring Daytime Running Lights. These turn your headlights on automatically during the day. But NHTSA says there's no data that proves DRLs improve safety, so they won't make a rule requiring them in the US.

Instead, NHTSA will say that intentionally disabling a vehicle while it's potentially driving on a busy highway will "impact safety in a negative manner", and they'll be completely right. The mandate isn't to give law enforcement a way to disable vehicles, but to disable vehicles "passively" when the car itself detects it's being driven by an impaired driver.

This rule will die in committee. We'll have self-driving cars before this technology ever becomes possible, and by then it won't be necessary.