The FBI doesn‘t want to talk about its Stingray devices. It definitely doesn‘t want local law enforcement agencies talking about them. It forces any agency seeking to acquire one to sign a very restrictive non-disclosure agreement that stipulates — among other things — that as little information as possible on IMSI catchers makes its way into the public domain, which includes opposing counsel, prosecutors‘ offices and judges. The NDAs also instruct agencies to drop prosecutions if disclosure appears unavoidable. We know this because two NDAs have actually been obtained through Freedom of Information requests.