Abstract: In Kansas v. Glover, the Supreme Court will consider whether a police officer has reasonable suspicion to believe that a vehicle is being driven by its registered owner — as opposed to some other authorized driver — when the sole fact known to the officer at the time of the stop is that the registered owner is not, in fact, lawfully allowed to drive any vehicle at all. This essay, adapted from an amicus brief filed in the Glover case, argues that the proper Fourth Amendment analysis in that case is unavoidably empirical in nature: The key question in the case can and should be resolved by real-world data, which the State in Glover was well-positioned to collect and present. Because it failed to do so, the State did not satisfy its burden of proof, and injected a narrow but significant error into the case that requires suppression, even if that result would not necessarily obtain in other cases arising in similar circumstances.