The federal prosecution of the two border guards, Ramos and Compean, began with the prosecution citing a constitutional decision written by Justice White which found an officer could have no authority to shoot a fleeing suspect if the officer did was not sure the suspect had a gun (Tennessee v. Garner, 471 US 1, 1985) – which Ramos and Compean honestly admitted they did not – which sole point is what making the shooting a federal civil right case hung upon.
The ruling was aimed at practices like Tennessee’s which routinely allowed officers to shoot fleeing suspects (an New York State’s not too much earlier – which had a rule that every police officer was to fire a warning shot over the head of every fleeing suspect and then shoot to kill – saw an example of this on a 1960ish episode of “Naked City”) which routinely allowed officers to shoot fleeing suspects.
The opinion of the Court was written specifically for a case of shooting a young teenage burglar who was climbing over a fence in the dark – and who had given the officer no cause to believe he was armed. In other words the opinion was written to do away with routine shooting of fleeing suspects (a then wide spread practice) – and was not nuanced as to the degree of danger facing the officer.
The border guard shot at a fleeing Mexican suspect who had marked himself as a drug dealer by seriously assaulting the officer’s partner (illegal immigrants never assault officers, ditto for coyotes), had abandoned a truck which likely therefore contained enough illegal drugs to put him behind bars for most of his life, and could be assumed to have a gun to protect said shipment: could therefore be plausibly feared to be willing to escape at any cost (A.K.A., armed and dangerous) – unlike a neighborhood teen climbing over a fence.
The Supreme Court decision specifically ruled out shooting if the officer was uncertain a fleeing suspect had a gun – but did not specify taking away the officer’s discretion to shoot without certain knowledge the suspect was gun armed where the totality of circumstances (clearly in this case) announced mortal danger to the officer’s life.
In a more perfect world the border guards' case would be an occasion for a more delineated precedent ("good luck").