Agent Lonnie Swartz killed Mexican citizen Jose Antonio Elena Rodriguez in 2012, after shooting the teenager from across the border in Arizona.
Swartz, standing on an embankment on U.S. soil, shot through a border fence and struck Rodriguez about 10 times. "I acted in self-defense, in response to a group of stone-throwers," the agent explained at the time.
However, Rodriguez's relatives claim that the teenager was walking peacefully down one of the streets in Nogales, a city located on the northwest border of the Mexican state of Sonora.
"The Border Patrol agent who killed 16-year-old Mexican Jose Antonio Elena Rodriguez in 2012 is acquitted."
Swartz was criminally prosecuted for the shooting but was acquitted at both trials, according to local sources.
The Supreme Court's ruling in favor of not getting justice for a border attack is not isolated. On Thursday, it dismissed a lower court ruling against another border patrol agent for shooting a 15-year-old Mexican boy dead from across the border in Texas.
On those cross-border incidents, last week's Supreme Court decision prevents civil rights lawsuits by foreign nationals in US federal courts when the person who is injured or killed was not on American soil, according to local media.