PHOENIX — Two Border Patrol agents assigned to Southern Arizona are suing the agency, accusing the agency’s Tucson Sector chief of illegally retaliating against them for publicly exposing illegal practices.

The lawsuit, filed Wednesday in U.S. District Court in Tucson, claims that Robert Gilbert suspended the law enforcement powers of agents Juan Curbelo and William Leafstone Jr., who both live in Douglas, because they publicly disclosed a practice of “shotgunning” by the Border Patrol. That practice, according to the lawsuit, involves stopping vehicles without reasonable suspicion that any crime has been committed.

Since August 2007 the pair have instead been assigned to build fences along the border. And Curbelo also drew a two-month maintenance assignment, with his duties including painting guardrails, mowing grass and unclogging sewage lines.

Dove Haber, a Border Patrol agent who handles media inquiries, said Wednesday her agency does not comment on pending litigation.

According to the lawsuit, the two agents’ problems began in 2006 when Curbelo’s ex-wife, Concepcion, and children were stopped by a Border Patrol agent near Rodeo, N.M. She was charged with possessing and transporting marijuana.

The lawsuit says Curbelo and Leafstone reviewed the arrest report and found “numerous inconsistencies that were an effort to cover up an obvious lack of reasonable suspicion” for having stopped the vehicle in the first place.

Curbelo eventually contacted the Border Patrol’s Office of Inspector General to complain, not only about the “shotgunning,” but also other concerns about how his ex-wife’s arrest was handled, concerns Leafstone also shared with that office.

Leafstone also agreed to testify on behalf of Curbelo’s ex-wife at a court hearing, with the result that the judge concluded the traffic stop was illegal and the charges against her eventually dismissed. Within days of that hearing, the lawsuit says, Gilbert directed both to turn in their badges and firearms, with the reason being given that the two agents had “divulged sensitive Border Patrol information.”

The lawsuit, filed on their behalf by the American Civil Liberties Union, contends the officers were punished for exercising their First Amendment free speech rights, and in particular the right of Leafstone to testify in a legal proceeding. It seeks a court order returning the two men to their full job positions and responsibilities.

“It’s our contention that the Border Patrol is punishing these officers for breaking the agency’s ‘code of silence’ and shedding light on a practice that brazenly violates the privacy rights of motorists,” said Peter Simonson, executive director of the ACLU of New Mexico in a prepared statement.

“Rather than being suspended from their jobs, Agents Curbelo and Leafstone should be congratulated for taking a principled stand, knowing full well that it might not sit well with some of their fellow officers,” he said.