Investigators are in a fight in the offices and cubicles of any law enforcement agency… one where the other side is gradually getting the better of them. Any subscriber to a technical law enforcement listserv can watch it happen in real time—ICAC (Internet Crimes Against Children Task Force) investigators, the folks who run wiretap systems, and cyber investigators will see a steady stream of questions and complaints. “Anyone have a real person I can call at Company A? They just kicked back my search warrant without any explanation, and no one is answering my emails.” Or “Anyone know what kind of evidence I can get from WhatsApp? My wiretap target just switched over from phone calls.” It goes on every day, and these days, law enforcement calls it “Going Dark.”