The FBI's use of a Patriot Act provision that lets it make secret requests for subscriber information from Internet service providers <A HREF="http://news.zdnet.com/2100-9595_22-6067604.html?tag=zdnn.alert">drew scrutiny from U.S. senators</A> on Tuesday. At a wide-ranging oversight hearing convened by the Senate Judiciary Committee, FBI Director Robert Mueller faced a number of questions from Democrats voicing concern over the scope of the controversial investigative tactic, known as a National Security Letter, or NSL. Federal law requires communication service providers to provide records about individuals in response to such letters, which do not require the use of a court warrant. Legal challenges to that measure's constitutionality are still pending.