Border Patrol agents boarded a bus and asked for citizenship papers. Is that legal?
A special agent from Immigration and Customs Enforcement (ICE) searches a vehicle heading into Mexico at the Hidalgo border crossing on May 28, 2010 in Hidalgo, Texas (AFP Photo/Scott Olson)

MIAMI — U.S. Border Patrol agents took someone off a Greyhound bus outside the Fort Lauderdale station after allegedly asking everyone on board for proof of citizenship, according to witness video and immigration advocates.