deciding Chimel v. California (1969), the Supreme Court elucidated its previous decisions. It held that when an arrest is made, it is reasonable for the officer to search the arrestee for weapons and evidence. However, in Riley v. California (2014), the Supreme Court ruled unanimously that police must obtain a warrant to search an arrestee's cellular phone. The Court said that earlier Supreme Court decisions permitting searches incident to an arrest without a warrant do not apply to "modern cellphones, which are now such a pervasive and insistent part of daily life that the proverbial visitor from Mars might conclude they were an important feature of human anatomy," and noted that U.S. citizens' cellphones today typically contain "a digital record of nearly every aspect of their lives—from the mundane to the intimate." Border search exception Searches conducted at the United States border or the equivalent of the border (such as an international airport) may be conducted without a warrant or probable cause subject to the border search exception. Most border searches may be conducted entirely at random, without any level of suspicion, pursuant to U.S. Customs and Border Protection plenary search authority. However, searches that intrude upon a traveler's personal dignity and privacy interests, such as strip and body cavity searches, must be supported by "reasonable suspicion". The U.S. Courts of Appeals for the Fourth and Ninth circuits have ruled that information on a traveler's electronic materials, including personal files on a laptop computer, may be searched at random, without suspicion. Foreign intelligence surveillance The Supreme Court decision in United States v. U.S. District Court (1972) left open the possibility for a foreign intelligence surveillance exception to the warrant clause. Three United States Courts of Appeals have recognized a foreign intelligence surveillance exception to the warrant clause, but tied it to certain requirements. The exception to the Fourth Amendment was formally recognized by the United States Foreign Intelligence Surveillance Court of Review in its 2008 In re Directives decision. The lower court held that "a foreign intelligence exception to the Fourth Amendment's warrant requirement exists when surveillance is conducted to obtain foreign intelligence for national security purposes and is directed against foreign powers or agents of foreign powers reasonably believed to be located outside the United States." Despite the foregoing citation the Fourth Amendment prohibitions against unreasonable searches and seizures nonetheless apply to the contents of all communications, whatever the