JUSTICE ALITO, concurring. I join the opinion of the Court on the understanding that it holds no more than the following: On a public right-of[1]way that traverses an Indian reservation and is primarily patrolled by tribal police, a tribal police officer has the au[1]thority to (a) stop a non-Indian motorist if the officer has reasonable suspicion that the motorist may violate or has violated federal or state law, (b) conduct a search to the ex[1]tent necessary to protect himself or others, and (c) if the tribal officer has probable cause, detain the motorist for the period of time reasonably necessary for a non-tribal officer to arrive on the scene.