In a potentially groundbreaking decision, a federal appeals court in Louisiana has ruled that a U.S. Border Patrol agent faces legal liability for using deadly force against a Mexican teenager on the other side of the border. It’s the first time that an appeals court has provided a non-U.S. citizen south of the border with the protections of the U.S. Constitution.

Officer Jesus Mesa Jr. allegedly shot and killed a 15-year-old, Sergio Adrian Hernández Guereca, in 2010 while the two were on opposite sides of the border.

Hernández’s relatives sued Mesa claiming he had exceeded his legal authority by firing into a foreign country during the incident.

The matter wound up before a three-judge panel in New Orleans, where the court proclaimed Mesa may have committed “an official abuse of power so arbitrary as to shock the conscience.”

The panel’s decision—which was a 2-1 split among the judges—allows the lawsuit to proceed, assuming Mesa’s attorney does not convince the full appellate court to review the decision.

While re-affirming an established rule that government immunity prevents the Border Patrol from being sued, the judges ruled that the agent was legally liable for the killing because his actions exceeded his authority.

“No reasonable officer would have understood Agent Mesa’s alleged conduct to be lawful,” they wrote in their decision.

Robert Hilliard, attorney for the Hernández family, called the ruling “a huge human rights victory,” according to The Los Angeles Times. “It gives you a voice inside a U.S. courtroom. They have to focus on, ‘Did the border agent do something wrong?’”

Mesa’s legal counsel, Randolph Ortega, accused the judges of overreach by extending “the protections of the U.S. courts into foreign countries where the U.S. does not have any jurisdiction.”

The news follows other controversial developments in recent weeks involving the Border Patrol, including the surfacing of an internal and highly critical report of the agency’s deadly force policies involving illegal immigrants.

Hernández is one of 22 people killed by Border Patrol agents, mostly on the Southwest border, between January 2010 and December 2013, the Times reported. Although there have been a handful of suspensions and reprimands of agents, none—including Mesa—has been terminated by the agency as a result of any of the shootings.

-Noel Brinkerhoff, Danny Biederman

To Learn More:

Border Patrol Agent Can Be Sued in Fatal Shooting, Court Rules (by Joseph Tanfani and Brian Bennett, Los Angeles Times)

Was Removal of Border Patrol Abuse Investigator just a Cover-Up for a Failed System? (by Noel Brinkerhoff and Steve Straehley, AllGov)

Border Patrol Agents Kill 27-Year Resident of U.S. and 15-Year-Old Boy (by Noel Brinkerhoff, AllGov)