Ryan Lizza: Why Won’t Obama Rein in the N.S.A.? : The New Yorker:

“In recent years, Americans have become accustomed to the idea of advertisers gathering wide swaths of information about their private transactions. The N.S.A.’s collecting of data looks a lot like what Facebook does, but it is fundamentally different. It inverts the crucial legal principle of probable cause: the government may not seize or inspect private property or information without evidence of a crime. “

A very thorough article on all things NSA and privacy. Emphasis mine