By David K. Shipler
The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the person or things to be seized.
--The Fourth Amendment to the US Constitution
The FBI, yet again, lied to the court, whose chief judge didn’t do her job properly and then excoriated the FBI. Republicans, who enacted and defended the secret system that permits such abuse, are suddenly in high dudgeon since the victim is one of their own. That’s the brief summary of the controversy over surveillance done on Carter Page, a campaign aide to Donald Trump. Whether something good comes out of the episode is an open question.
There are basically two legal ways for the government to listen to your phone calls, read your emails, search your house, and invade other areas of your private life. One is with a traditional search warrant, signed by a judge after law enforcement swears that probable cause exists to believe that certain evidence of a specific crime will be found at a particular place and time. The other is with a secret court order under the Foreign Intelligence Surveillance Act (FISA), which requires something quite different: probable cause that you are an agent of a foreign power, meaning either a government or a terrorist organization. No crime need be involved, and the standard of particularity is largely waived.
Other differences are notable. In a criminal case, the warrant is eventually disclosed and might be presented to the target at his door if he’s home as police arrive to do the search. He ultimately learns details of the searches. Theoretically, he should be able to see the affidavit on probable cause that the police submitted to the judge, so his lawyer can challenge the warrant’s basis and move in court to suppress the resulting evidence. However, in the experience of Richard Foxall, a defense attorney in California, judges rarely allow the defense to inspect the affidavits. (See Foxall's comment below.) That check on law enforcement doesn’t prevent all official wrongdoing, but it helps.
No such transparency exists in FISA warrants. Not only are they issued in secret by judges in a secret court, they are executed without notice to the target and are never disclosed unless the government chooses to use the resulting evidence in a criminal trial, and even then the affidavits themselves are usually considered classified. Occasionally the FISA material is used as a basis for an ordinary criminal warrant, but defense lawyers are usually blocked from seeing the original application.