There is. A law which requires carriers to provide sufficiently accurate cell phone location data so they can send it along with 911 calls.

https://www.fcc.gov/consumers/guides/911-wireless-services

"Phase II E911 rules require wireless service providers to provide more precise location information to PSAPs; specifically, the latitude and longitude of the caller. This information must be accurate to within 50 to 300 meters depending upon the type of location technology used."

Not the law I'm guessing you were after, huh?

Sad thing is this has been going on since the late 1990s, back then they had lower level reps at AT&T handling law enforcement location requests manually. Knowing a few of them, it took forever for those former reps to get cellphones due to a fear of being tracked, having dealt with those requests.

I've also noticed multiple in that group will purposefully leave their phone behind & drive their older cars when they choose to have a tracking free day, even 2 decades later exposure to how easy it is to pull live location data still notably impacts their behavior.