Accusing Greyhound of allowing its buses to become “rolling traps” where U.S. Customs and Border Protection (CBP) agents are permitted to conduct warrantless raids and interrogate immigrants at will, 10 local and state affiliates of the ACLU sent a letter (pdf) to the company on Wednesday arguing that such searches are unconstitutional and urging the company deny access to officials who don’t present a warrant.

“Greyhound has a Fourth Amendment right to deny CBP permission to board and search its buses without a judicial warrant.”
—ACLU”Greyhound should be in the business of transporting passengers, but instead is allowing intimidating interrogations and searches,” Monica Andrade, attorney and legal fellow with ACLU of Michigan Skadden, said in a statement. “These searches violate the rights of passengers, who simply want to arrive to their destinations safely. They should not be subject to warrantless arrests and the threat of deportation.”

While Greyhound insists that it is “required” to cooperate with CBP agents if they ask to board one of their buses, ACLU insists in its letter that it is “aware of no such requirement.”

“Rather, Greyhound has a Fourth Amendment right to deny CBP permission to board and search its buses without a judicial warrant,” the letter states.