Can law enforcement legally monitor phone calls?

At this point, law enforcement officers and intelligence agencies can seek permission from the courts to enact surveillance of telephone and computers as part of an investigation. They are authorized to do so by the Wiretapping Act of 1968, the Communications Assistance for Law Enforcement Act of 1994 (CALEA), and the Patriot Act of 2001. Investigations involving monitoring phone calls must be specifically for solving a criminal case or intended for national security purposes.

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