Jameel Jaffer and Brett Max Kaufman in Slate.

James Clapper, the director of national intelligence, has been harshly criticized for having misled Congress earlier this year about the scope of the National Security Agency’s surveillance activities. The criticism is entirely justified. An equally insidious threat to the integrity of our national debate, however, comes not from officials’ outright lies but from the language they use to tell the truth. When it comes to discussing government surveillance, U.S. intelligence officials have been using a vocabulary of misdirection—a language that allows them to say one thing while meaning quite another. The assignment of unconventional meanings to conventional words allows officials to imply that the NSA’s activities are narrow and closely supervised, though neither of those things is true. What follows is a lexicon for decoding the true meaning of what NSA officials say.

A lexicon for understanding the words U.S. intelligence officials use to mislead the public.