Continuing with James Bamford's work on the NSA, 'Body of Secrets'

....Among the reforms to come out of the Church Committee investigation was the creation of the Foreign Intelligence Surveillance Act (FISA), which for the first time outlined what NSA was and was not permitted to do. The new statute outlawed wholesale, warrantless acquisition of raw telegrams such as had been provided under Shamrock. It also outlawed the arbitrary compilation of watch lists containing the names of Americans. Under FISA, a secret federal court was set up, the Foreign Intelligence Surveillance Court. In order for NSA to target an American citizen or a permanent resident alien—a "green card" holder—within the United States, a secret warrant must be obtained from the court. To get the warrant, NSA officials must show that the person they wish to target is either an agent of a foreign power or involved in espionage or terrorism.

But because these issues fall under the jurisdiction of the FBI within the United States, NSA seldom becomes involved. Thus, according to a senior U.S. intelligence official involved in Sigint, NSA does not target Americans at home. "I want to make it clear," said the official, "[that] we do not intentionally target known U.S. persons in the United States— period. And therefore, we don't go to court to get a warrant to target any such people because we don't do any of those ... FBI worries about spies in the United States." The same goes for foreigners suspected of terrorism, he said. "Osama bin Laden . . . comes into the United States, he crosses the border," said the intelligence official. "We wouldn't do the guy. It would be FBI who'd do him, because he's a terrorist in the United States." Thus, the vast majority of the 886 eavesdropping warrants approved by the Foreign Intelligence Surveillance Court in 1999—the highest number ever—were from the FBI.

Judicial protections, however, stop at the border. "FISA doesn't cover the U.S. person who's outside the United States," added the official. To target Americans outside the country, all that is needed is the approval of the U.S. attorney general. Nevertheless, the number of Americans targeted by NSA overseas is very small. "At any one time," said the senior intelligence official, "there may be five. . . . These persons are—there's virtually no doubt that they are agents of foreign powers. Either they're terrorists or they're some kind of officer or employee of a foreign government. We're not talking about Jane Fonda."[don't even get me started on our star chamber.republic my ass.DC]
https://exploringrealhistory.blogspot.com/2020/01/part-10-body-of-secretsmuscle.html