Merrill is now able to reveal that the FBI believes it can force online companies to turn over the following information simply by sending an NSL demanding it: an individual’s complete web browsing history; the IP addresses of everyone a person has corresponded with; and records of all online purchases.

The FBI also claims authority to obtain cell-site location information with an NSL, which effectively turns a cell phone into a location tracking device. In court filings, the FBI said that at some point it stopped gathering location data as a matter of policy, but that it could secretly choose to resume the practice under existing authority.

Source: Revealed: What info the FBI can collect with a National Security Letter

That’s a hell of a lot of information they can collect without a court warrant… And they’ve been doing it for 11 years so far!