A federal appeals court ruled Monday that a Mexican teenager killed by a Border Patrol agent was protected by the U.S. Constitution, even though the teen was on Mexican soil when he was shot. The ruling from the 5th U.S. Circuit Court of Appeals means the family of 15-year-old Sergio Adrian Hernandez Guereca can move forward with a civil lawsuit against the agent. “This recognizes human rights belong to everyone. Not just American citizens,” or h…