When you cross into or out of the United States, whether in a car or at an airport, you enter a special zone where federal agents have unusual powers to search your belongings—powers they don’t have elsewhere in the country. The high standard set by the Fourth Amendment, which protects people against unreasonable searches, is lowered, and the Fifth Amendment, which guards against self-incrimination and prevents the government from demanding computer passwords or smartphone PINs, is rendered less effective.
These special rules allowed a customs officer at the Houston airport to ask a NASA engineer to give up the passcode to his smartphone last month.
