The Supreme Court on Tuesday ruled that a Border Patrol agent who fired from US soil and fatally shot a child on the Mexican side of the border can't be sued by his family.

In a 5–4 ruling, the court's five conservative justices agreed with the government and upheld a lower court's decision to dismiss the case against the agent because 15-year-old Sergio Adrian Hernandez Guereca wasn't on US soil when he was killed. The court's four liberal justices dissented.

The court's decision not only bars Hernandez's family from suing Border Patrol Agent Jesus Mesa for damages but also makes it harder for all foreign nationals to sue federal officers for civil rights violations.

The case is centered on the 2010 cross-border fatal shooting of Hernandez, who was in a concrete culvert that separates El Paso, Texas, and the Mexican city of Ciudad Juárez.

Hernandez's family said the teenager was playing a game with his friends running across the culvert to touch the fence on the US side of the border and running back into Mexico. Mesa said Hernandez and his friends were trying to enter the US without authorization and had thrown rocks at him.

After Hernandez ran back into Mexico, Mesa fired two shots at him; one struck and killed him.

His family sued Mesa claiming Hernandez's Fourth and Fifth Amendment rights had been violated.

Justice Samuel Alito, writing for the majority, said the case "has foreign relations and national security implications" and said it's Congress who should decide whether lawsuits such as the one before them should be allowed to go forward.

"Congress, which has authority in the field of foreign affairs, has chosen not to create liability in similar statutes," Alito said. "Congress’s decision not to provide a judicial remedy does not compel us to step into its shoes."

In a dissenting opinion, Justice Ruth Bader Ginsburg said the family should be able to sue when a US officer acts on one side of the border even though the impact of the action is suffered abroad. Ginsburg also disagreed with Alito and said neither US foreign policy nor its national security is endangered by the litigation.

"Mesa’s allegedly unwarranted deployment of deadly force occurred on United States soil," Ginsberg wrote. "It scarcely makes sense for a remedy trained on deterring rogue officer conduct to turn upon a happenstance subsequent to the conduct—a bullet landing in one half of a culvert, not the other."

ACLU attorney Lee Gelernt, who argued the case filed by the family of José Antonio Elena Rodríguez, said the gravity of Tuesday's ruling could not be clearer given the Trump administration’s militarized rhetoric and policies targeting some people at the border.

"Border agents should not have immunity to fatally shoot Mexican teenagers on the other side of the border fence," Gelernt said in a statement. "The Constitution does not stop at the border.”