The Supreme Court determined that a car is included in the "effects" covered by the constitutional amendment. It also found that the state hadn't identified an exception to that rule that would apply in this case, and that claims this would be an "inevitable discovery" (and thus exempt from requiring a warrant before the search) didn't hold up. Police officers weren't even looking for a warrant at the time they took data from the car's Event Data Recorder, according to the ruling.
Not surprisingly, the reversal has already pleased privacy advocates. The ACLU, which filed a friend-of-the-court brief supporting Mobley in the case, argued that the court had acknowledged the "danger of warrantless access" to car data. Black boxes like the EDR often contain extremely detailed information about not just the behavior of the car, but connections to other systems that can include phone contacts, location history and other sensitive info. The civil rights group also contended that this was no different than searching other computers without a warrant -- it just happens to be a "computer on wheels," ACLU staff attorney Nathan Freed Wessler said.
Barring a US Supreme Court challenge, this could have a significant impact on how law enforcement searches cars in the future. Simply put, they'll have to make clear that they either have or are seeking a warrant before they even think of taking data from a car. The timing is appropriate as well. Numerous automakers are developing intensely connected cars that could have a raft of personal data. Without privacy protections, American police could theoretically abuse their power and obtain details about your personal life with few consequences.