An anonymous reader writes with this lead from Help Net Security's story on a topic we've touched on here many times: the broad powers arrogated by the Federal government in the form of National Security Letters: On Monday, after winning an eleven-year legal battle, Nicholas Merrill can finally tell the public how the FBI has secretly construed its authority to issue National Security Letters (NSLs) to permit collection of vast amounts of private information on US citizens without a search warrant or any showing of probable cause. The PATRIOT Act vastly expanded the domestic reach of the NSL program, which allows the FBI to compel disclosure of information from online companies and forbid recipients from disclosing they have received an NSL. The FBI has refused to detail publicly the kinds of private data it believes it can obtain with an NSL. A key sentence from the same story: "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." Reader Advocatus Diaboli adds this, from The Intercept: One of the most striking revelations, Merrill said during a press teleconference, was that the FBI was requesting detailed cell site location information — cellphone tracking records — under the heading of "radius log" information. Traditionally, radius log refers to a user's attempts to connect to a server or a DSL line — a sort of anachronism given the progress of technology. "The notion that the government can collect cellphone location information — to turn your cellphone into a tracking device, just by signing a letter — is extremely troubling," Merrill said.