Senior U.S. District Judge David Briones on Aug. 11 threw out the lawsuit filed against the U.S. over the 2010 shooting of Sergio Adrian Hernandez Guereca of Ciuidad Juarez.
The El Paso Times reported Thursday that the ruling says the boy was shot while in Mexico and no statutes apply in suing the U.S. government.
Family attorney Bob Hilliard on Thursday told The Associated Press that he'll appeal.
A lawyer for Agent Jesus Mesa Jr. didn't immediately return a message for comment. U.S. investigators have said the agent was trying to arrest illegal immigrants when he was targeted by rock throwers.