Due Process is one of the greatest protections the Constitution offers us. It's an affront to a free society that the government can place your name on a list without your knowledge and deny you basic rights (e.g. purchasing/owning a firearm) and liberties (e.g. flying). If the government feels so strongly about putting you on a watchlist, they should make their case in a court of law where they have the full burden of proof and the accused can defend themselves.