The FBI ultimately acknowledged that she ended up on there because an agent investigating her had checked the wrong box on a form, said her attorney, Elizabeth Pipkin.

Chillingly, the U.S. Justice Department never disclosed why Ibrahim was being investigated in the first place.

To Pipkin, what happened to Ibrahim is a cautionary tale of the problems with controversial terrorist watch lists, which this week are a focus of Congress’ struggle to find a way to prevent suspected terrorists from buying guns.