Hilliard represented the family of Sergio Hernández, an unarmed 15-year-old Mexican citizen who was shot and killed by a U.S. Border Patrol agent in 2010. Hernández was standing on Mexican soil when shot. Hilliard also represented the family of Guillermo Arevalo Pedraza, who was killed under similar circumstances by a different U.S. Border Patrol agent.[24] The cases sparked a confrontation between former Mexican President Felipe Calderón and former U.S. Secretary of State Hillary Clinton.