It can feel surreal when your passport is valid, your visa situation seems fine, and border officials still pull you aside for hours. But at an airport, seaport, or land crossing, customs and border officers have broad legal authority to question travelers before deciding whether to admit them or clear them through inspection. In the United States, that authority mainly sits with U.S. Customs and Border Protection, or CBP. So yes, even with a valid passport, extra questioning can still be legal.