Federal agents found heroin during a warrantless search of a backpack that they seized from Petitioner as he exited a bus. Agents then arrested Petitioner for possessing with intent to distribute the heroin found by their search. Respondent later justified the search as having taken place "incident to arrest." It is undisputed that, months before the backpack search, the agency showed probable cause to believe that Petitioner had conspired to distribute drugs. On the day of the backpack's search, there was no evidence introduced into the record that agents had effectively arrested Petitioner based on probable cause for any particular offense, or that they were about to do so, before they searched and found the heroin.

The question presented is:

Whether the Fourth Amendment's "search incident to arrest" exception permits a warrantless search anytime agents had probable cause to believe that a defendant had committed some arrestable offense -- even when agents had made no arrest, and were not already going to make one, before the search.

Whether the Fourth Amendment's 'search incident to arrest' exception permits a warrantless search anytime agents had probable cause to believe that a defendant had committed some arrestable offense -even when agents had made no arrest, and were not already going to make one, before the search