“Because the lists are shrouded in official secrecy, the public knows very little about them. But even a glancing review of the information we do have suffices to show what folly it would be to pretend that those lists offer a reliable measure of who is truly dangerous. According to the government’s March 2013 Watchlisting Guidance, “concrete facts are not necessary” to make out reasonable suspicion. In fact, the guidance carves out a number of loopholes that dispense with reasonable suspicion altogether. Immediate family members of a suspected terrorist can be listed, as can other associates not themselves known or suspected to be involved in anything — and, finally, individuals with only “a possible nexus” to terrorism. It is unclear what “a possible nexus” actually means, and whether it is any different from a mere hunch.” I help innocent people get off terrorism watch lists. As a gun control tool, they’re useless.