Given how powerful the three letter agencies are (especially the CIA), I'm not surprised the judiciary branch of the U.S. government agrees its constitutional.

Given how powerful the three letter agencies are (especially the CIA), I'm not surprised the judiciary branch of the U.S. government agrees its constitutional. The ACLU and many legal professionals think FISA is unconstitutional. There are roadblocks when trying to challenge FISA because of the secrecy, see: https://www.npr.org/2013/02/26/172998760/supreme-court-makes-it-harder-to-challenge-foreign-intelligence-surveillance-act https://www.npr.org/2013/02/26/172998760/supreme-court-makes...