A rare Sunday afternoon statement by the Office of the Director of National Intelligence responds to news reports that Jerry Nadler (D-N.Y.) was told in a Congressional briefing that the NSA could listen to Americans' phone calls without a warrant:
Here's what confused Nadler. While it is true that an American communication can be accidentally intercepted after an analyst makes a decision to intercept a foreign communication, it would be just plain illegal for an analyst who believes that his or her target is an American to begin the interception process, the content interception process, without a FISA warrant.
Here's where Nadler is not entirely wrong: The NSA has a bit of a safe harbor period — details classified — if certain conditions are met, when it comes to an emergency interception of a domestic end of a telephone call or e-mail. Think: An actual ticking time bomb scenario.
But the Attorney General would likely be called into an emergency FISA meeting that day, and if the FISA court refuses to issue a warrant, the interception would stop. But an analyst cannot simply decide to start an emergency interception process without virtually the entire mothership at Ft. Meade being notified immediately.
My understanding is that NSA does not have this emergency authority at all for American citizens or corporations — only for American "facilities," which is a fancy word for physical or virtual targets based in America. If there's emergency situation involving an American, NSA sends a bulletin to the FBI through the National Counterterrorism Center in Virginia and lets them deal with it.
Remember, the upshot of the 2008 FISA amendments acts is that the NSA got expanded access to U.S. telecom switches and hubs in exchange for agreeing not to spy on Americans anywhere in the world without a FISA order. And again, the FBI usually does the interception if an American is involved. Doesn't matter where you are: If you're an American, you're protected by FISA. If you're an agent of a foreign power, or there's a reason to believe you're associated with a group of bad guys and you're not a U.S. person, the NSA can indeed begin to intercept your communications without a FISA order in certain, classified circumstances.