[the wall is] a set of procedures implementing a 1978 statute (the Foreign Intelligence Surveillance Act, or FISA) and federal court decisions interpreting it. In a nutshell, that law, as the courts read it, said intelligence investigators could conduct electronic surveillance in the United States against foreign targets under a more lenient standard than is required in ordinary criminal cases, but only if the "primary purpose" of the surveillance were foreign intelligence rather than a criminal prosecution.

....The Patriot Act, enacted after 9/11, together with an unprecedented appeal to the Foreign Intelligence Surveillance Court of Review, paved the way for the Justice Department to permit largely unrestricted information-sharing between intelligence and criminal investigators because the law changed the legal standard that had given rise to the guidelines in the first place. The Patriot Act says that electronic surveillance can be conducted in the United States against foreign threats as long as a "significant purpose" -- rather than the "primary purpose" -- is to obtain foreign intelligence.

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My view: Intelligence gathering is the wrong job for a law enforcement agency. The FBI is not cut out to be an intelligence gathering agency.I think the wall is a good thing. But it looks like it's about to come tumbling down.