I read a lot of new Fourth Amendment cases, and in the last year or two I've noticed something interesting: Body-worn cameras seem to be changing Fourth Amendment law. To be clear, the cameras aren't having an explicit effect. Courts don't have camera-specific rules. But body-worn cameras are changing how courts review police-citizen interactions. The ability to "go to the tape" allows courts to reconstruct in detail exactly what happened. And that lets courts scrutinize much more closely what the police are doing—and to adopt doctrines that rely on that second-by-second scrutiny.
A number of the relevant cases involve the length of traffic stops. Traffic stops are the most common police-citizen interaction, and a stop for speeding or a broken taillight can often turn into something more. Given that, what happens during a traffic stop is super important. One of the important doctrinal tool to limit traffic stops (maybe the most important) is the time element. In Rodriguez v. United States, in 2015, the Court held that the permitted time of a traffic stop is determined by the time that an officer actually did or should have completed the mission of the stop — the mission being the safety-related rationales that permit traffic stops in the first place, like writing a ticket, making sure the car is registered, the driver has a valid license, etc.
Rodriguez came at an interesting moment. It introduced a time-based test at a time when police body-worn cameras were coming into widespread use. And by creating a test that distinguishes things within the mission of the stop from things outside the mission, the Court created a test that in theory could hinge on pretty specific, second-by-second inquiries into time. Before body-worn cameras, though, that would have been essentially impossible. Courts trying to reconstruct what happened during traffic stops would be stuck with the old tools of relying on memory from a long past event.
