Orin Kerr of the Volokh Conspiracy once again leads us down a fascinating rabbit hole in the legal world, this time somehow finding the intersection between self-driving cars and law enforcement. If that rings in your ears like a curious combination you’re not alone, but Kerr quickly makes his point in a fashion which is tough to argue.

Consider the first point that he brings up. Traffic stops comprise a great deal of law enforcement activity in this country, and in the only ones which make it onto the evening news, much of it winds up having very little to do with whether or not a suspect’s tail light is malfunctioning.

Although part of the police interest in traffic enforcement relates to traffic safety, a lot of it also relates to enforcing other laws. The Supreme Court has repeatedly held that the police can use traffic stops pretextually. What the officer is really trying to do doesn’t matter, the court has ruled, as long as the officer has a valid basis for stopping a car for a traffic violation. The reason is that Fourth Amendment doctrine rejects subjective intent as a basis for determining whether a stop is lawful. So long as the officer had a valid basis for a stop (speeding 55 in a 50 zone), the fact that the officer is really acting for other reasons (determining if there are drugs in the car) is irrelevant.

Of course, the vast, vast majority of traffic stops are just that… investigations of infractions of traffic laws. They must number in the hundreds of thousands every day and you never hear a peep about them unless it happens to you. But then there are those that you do wind up hearing about. The traffic stop where the suspect is found to have drugs or illegal weapons in the car. The ones where they bolt from the vehicle and run or begin firing on the police. The list goes on.

So what happens in the future if virtually all traffic is comprised of self-driving cars, particularly if they are Uber or Lyft vehicles in most cases? In theory they will always obey the law. Software can fail and accidents may happen, but what grounds would the police have for investigating the passenger in the back seat who neither owns nor operates the vehicle? Unless the cop is trotting out the drug sniffing dog there’s not much of a conversation to be had with the suspect.

So the police may be left without one of their primary methods of running down bad guys. But Kerr points out another aspect of the technology which may actually work in their favor. Will the cops be able to summon up the records of the vehicles at will to see where you were going on a particular day?

In the case of records kept by ride-sharing services, one obvious legal question is whether the records of past trips are protected under the Fourth Amendment or statutory privacy laws. The traditional Fourth Amendment answer would be that the service user does not have rights in the information. The records are just the company’s business records of where their cars went, and that is the company’s business record and not the customer’s. Whether that remains the law is open right now, thanks to the recent grant in Carpenter v. United States, the cell-site case. It may be that Carpenter will make those records protected by a warrant requirement, so that reconstruction is permitted but requires the government to establish probable cause that the trip will reveal evidence of a crime. As always, stay tuned.

Good point. Why should the police need a warrant with your name on it to get the records of the company that owns the vehicle? Nobody forced you to take an Uber that day and the fact that you were in the car is incidental to a request to find out where the car went. This doesn’t lock down many cases in terms of proving a crime was committed, but it can at least place suspects in the vicinity at the time, proving opportunity.

Just some food for thought for all of you futurists out there. Of course, Kerr completely ignores the issue of what will happen when SKYNET is activated and the cars begin simply hurling you off of cliffs, but most of the media is afraid to tackle that one.