It sounds a bit like Big Brother: Police can place a GPS device on your car to follow all of your movements, for any length of time. The Supreme Court on Tuesday is scheduled to hear arguments about whether investigators need to get a warrant before doing so.

Legal experts say the case, which stems from a D.C. nightclub owner’s conviction on drug charges, is one of the most important Fourth Amendment cases in decades, and will determine how police conduct investigations and privacy in the high-tech age.