In the case, Officer Mehrer pulled over a truck even though he hadn’t seen the driver break any rules. Mehrer had run the truck’s license plate, learned that the truck was licensed to Charles Glover, Jr., and then saw that Charles Glover, Jr.’s license had been revoked. So Mehrer assumed Glover was driving and pulled the truck over. The officer did not attempt to confirm the identity of the driver before making the stop.

It turned out that Charles Glover, Jr. was driving, and the officer gave Glover a ticket for driving while his license was revoked.

Reasonable assumption for the Fourth Amendment?

In one sense, this is a reasonable assumption. The State of Kansas (on behalf of Mehrer) argues so. People usually drive their own cars, so the officer reasonably assumed the person with the revoked license was driving.

But the Supreme Court of Kansas ruled the opposite view: that the officer had not acted reasonably. The Fourth Amendment gives individuals protection from being pulled over unless the officer has “reasonable and articulable” suspicion that the person is committing, has committed or is about to commit a crime. In this case, the Kansas high court said, without specific facts identifying that the driver was the registered truck owner, the officer had no reason to assume the driver was violating the law.

The owner-is-the-driver assumption is generally not reasonable suspicion to make a traffic stop, the Kansas court concluded. Family members drive cars registered to other family members all the time. There’s no law against people driving cars that are registered to others, even when the owner’s license has been revoked. Although, in this case, the officer did have a suspicion that a specific law was being broken (driving without a revoked license), the officer did not have a reason to believe the driver was violating the law. The officer would have had to find a specific fact connecting the driver to his suspicion of a crime in order to make the suspicion reasonable.

Kansas: you’re asking for “probable cause”

Kansas argues back: “reasonable suspicion” is a different standard than “probable cause.” Officer Mehrer did have “reasonable suspicion” to believe the driver had a revoked license: the driver was in the car of the person with the revoked license. That’s good enough. Additional facts to identify the driver was Glover would have given the officer a higher standard of proof: “probable cause.” That’s a different legal standard, and it’s not necessary here.

Minimal or major intrusion of privacy?

To the State of Kansas, a traffic stop is a minimal privacy intrusion. The state points out that driving comes with a large number of state regulations because it’s a dangerous activity that affects many people. In fact, Fourth Amendment law recognizes a lessened privacy right for individuals when driving than when they are in their homes or even out on the street. Thus, the state continues, getting pulled over goes with the territory, and it’s not a major interference.

Glover disagrees. First of all, Glover’s brief argues, a large number of people are driving cars that are not registered in their names. Millions of people have their licenses suspended at any given time. Kansas’s rule would allow officers to pull over anyone driving a car registered to individuals with revoked licenses, which is a lot of people and therefore a large privacy intrusion to the country in general. As technology advances (for example, with automated license plate readers), it’s quite possible that states will be able to take advantage of this large surveillance power and be able to stop cars for no reason at all. Glover argues that’s exactly the type of government behavior that the Fourth Amendment exists to prevent.

A traffic stop isn’t a minor privacy intrusion, Glover continues. Unlike a checkpoint stop, a roadside stop causes much more anxiety and takes much more time for the person who is stopped. Once a person is stopped, even if an officer realizes the person has done nothing wrong (like isn’t the person with the revoked license), the officer still will engage with the person, may interrogate the person and look around in the car. This rule, Glover says, will make subject people to these intrusive roadside stops without ever having done something wrong.

The United States filed a brief in support of Kansas in the case.

The Supreme Court will hear arguments on November 4, 2019.