According to the Supreme Court in U

According to the Supreme Court in U.S. v. Montoya de Hernandez, involving a detention at the border for drug investigation:

A) even routine customs searches at the border require reasonable suspicion.
B) any detention at the border that lasts more than 15 minutes is unreasonable.
C) detention beyond the scope of a routine customs search and inspection is always
Unreasonable.
D) the Fourth Amendment's balance of reasonableness is qualitatively different at the
International border than in the interior of the country.