On the heels of a series of reports detailing the U.S. government's practice of tracking private citizens' phone and internet use, President Obama on Friday sought to downplay the invasiveness of the procedure, assuring a California audience that "nobody is listening to your phone calls," and that any data tracking is governed by comprehensive oversight spanning all three branches of U.S. government...

...But he reminded Americans that these programs have been ongoing for years, and that Congress regularly reauthorizes the programs and receives updates on how they are conducted.

The Obama administration secretly won permission from a surveillance court in 2011 to reverse restrictions on the National Security Agency’s use of intercepted phone calls and e-mails, permitting the agency to search deliberately for Americans’ communications in its massive databases...

...the court in 2008 imposed an explicit ban — at the [Bush administration]’s request — on ... searches [of U.S. communications], that officials in 2011 got the court to lift the bar and that the search authority has been used.

Together the permission to search and to keep data longer expanded the NSA’s authority in significant ways without public debate or any specific authority from Congress...

...Officials would not say how many searches have been conducted.

...The court’s expansion of authority went largely unnoticed when the opinion was released, but it formed the basis for cryptic warnings last year by a pair of Democratic senators, Ron Wyden (Ore.) and Mark Udall (Colo.), that the administration had a “back-door search loophole” that enabled the NSA to scour intercepted communications for those of Americans.

The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.