For the moment, its still a “voluntary” request, as this article from The Atlantic points out – referring to Customs and Border Protection agents requesting ID from passengers deplaning on an SFO to JFK flight. As the author, Garrett Epps of the University of Baltimore Law School, points out, “voluntary” in legalese does not mean what ordinary people think it means. Supreme Court caselaw makes clear that officers may block an exit and ask for ID or permission to search. They aren’t required to tell the individual stopped that he or she may refuse: “while most citizens will respond to a police request, the fact that people do so, and do so without being told they are free not to respond, hardly eliminates the consensual nature of the response.”

Epps concludes: “Justice William O. Douglas once wrote that a regime of liberty includes “freedom from bodily restraint or compulsion, freedom to walk, stroll, or loaf.” A shadow is falling over that freedom, both for aliens and for citizens. Its loss will be devastating.”