The admission comes in a letter from the Office of the Director of National Intelligence declassifying statements that a top U.S. Senator wished to make public in order to call attention to the government’s 2008 expansion of its key surveillance law.

“On at least one occasion,” the intelligence shop has approved Sen. Ron Wyden (D-Ore.) to say, the Foreign Intelligence Surveillance Court found that “minimization procedures” used by the government while it was collecting intelligence were “unreasonable under the Fourth Amendment.” Minimization refers to how long the government may retain the surveillance data it collects. The Fourth Amendment to the Constitution is supposed to guarantee our rights against unreasonable searches.

Wyden does not specify how extensive this “unreasonable” surveillance was; when it occurred; or how many Americans were affected by it.

In the letter, acquired by Danger Room (.pdf), Wyden asserts a serious federal sidestep of a major section of the Foreign Intelligence Surveillance Act.