In 1967, the Supreme Court of the United States held that the requirements of the Fourth Amendment applied equally to electronic surveillance and to physical searches. "Katz v. United States", 389 U.S. 347 (1967). The Court did not address whether such requirements apply to issues of national security. Shortly after, in 1972, the Court took up the issue again in "United States v. United States District Court, Plamondon", where the court held that court approval was required in order for the domestic surveillance to satisfy the Fourth Amendment. 407 U.S. 297 (1972). Justice Powell wrote that the decision did not address this issue that "may be involved with respect to activities of foreign powers or their agents".