Greyhound said Friday it would prohibit U.S. Customs and Border Protection agents without a warrant from boarding its buses to conduct immigration checks as bus companies continue to face pressure from civil rights advocates over the practice. The announcement comes after an Associated Press report said a Jan. 28 Border Patrol memo contradicted Greyhound's stance that it had to allow the agents on its buses under federal law. In this Thursday, Feb. 13 photo, agents for Customs and Border Protection board a Greyhound bus headed for Portland, Ore., at the Spokane Intermodal Center, a terminal for buses and Amtrak in...