Can the U.S. government seize the passports of American citizens who it believes may travel abroad to join ISIS or other terror groups? Yep. The process is almost no-cost to the government, extra-judicial, can be made secret and requires a lengthy court process to even try to contest. No passport, no international travel, the ultimate no-fly tool against would-be jihadis. ...
And the procedure is ostensibly legal... but it has not been much used. Read van Buren's post to learn why.