These are the 2 major Supreme Court cases that protect cops who kill unarmed civilians

A grand jury's decision not to indict an officer who killed a 12-year-old holding a toy gun sheds light on a criminal-justice system that gives fairly broad deference to police officers' version of events.

As Business Insider's Natasha Bertrand reported, the prosecutor in the case of the 12-year-old said, "We don't second-guess police officers."

Two Supreme Court decisions set the precedent that gives such wide latitude to officers, as civil rights lawyer Chase Madar has pointed out in The Nation.

Both cases involve police violence in the 1980s against black males.

"The 'reasonableness' of a particular force must be judged from the perspective of a reasonable officer on the scene, rather than with the 20/20 vision of hindsight," one of those rulings found, signaling deference to the perspective of police officers.

That first case, decided in 1985, was initially viewed as a curb on police force. In Tennessee v. Garner, a Memphis police officer shot and killed a 15-year-old boy named Edward Garner - who incidentally shared a last name with Eric Garner, the man who died in an apparent "chokehold" on Staten Island last year.

The night he died, Edward Garner had burglarized a house and was unarmed and fleeing on foot when a police officer shot him in the back of the head. The teenager had $10 and a purse he'd stolen from the house on him. While the cop said he "figured" Garner was unarmed, he defended his actions under a Tennessee law that stipulated cops could "use all the necessary means to effect the arrest" of suspects who flee, according to the Supreme Court decision.

In effect, that Tennessee law said that cops could kill any fleeing suspect regardless of the potential risks they posed. The Supreme Court said in its 1985 decision that the Tennessee law went too far and was unconstitutional.

"While burglary is a serious crime, the officer in this case could not reasonably have believed that the suspect - young, slight, and unarmed - posed any threat," the court ruled.

In the future, the court ruled, a cop could only use deadly force if they have "probable cause to believe that the suspect poses a threat of serious physical harm, either to the officer or to others."

The ruling in Tennessee v. Garner said the use of force on a fleeing suspect has to be based on probable cause that they pose a threat. On its face, this seems a ruling that would empower police to use force when it's necessary to protect themselves or the public.

However, the decision was written broadly enough to pave the way for another decision in 1989 that gave cops fairly wide latitude to determine what kind of force was reasonable. In that case, Graham v. Connor, a diabetic named Dethorne Graham was confronted by police officers while having an insulin reaction.

Graham had asked his friend to drive him to a convenience store for orange juice, saw a long line, and hastily left the store to get it elsewhere. A cop noted his odd behavior and stopped the two friends after they got in their car.

Meanwhile, his friend tried to explain that Graham was a diabetic and pleaded with the cops to get him sugar.

"I've seen a lot of people with sugar diabetes that never acted like this. Ain't nothing wrong with the M.F. but drunk. Lock the S.B. up," one officer said, according to the court opinion.

The encounter with the police left Graham with a broken foot as well as cuts and bruises. The Supreme Court ultimately sent the case back for reconsideration by a lower court, and in doing so it specified the standard for determining whether the use of police force is "reasonable" under the Fourth Amendment (which gives individuals the right to be "secure in their persons.")

Here's that standard, which attorney Greg Wiley has written is "far more deferential to law enforcement personnel than it may first appear." From the 1989 opinion:

Our Fourth Amendment jurisprudence has long recognized the right to make an arrest or investigatory stop necessarily carries with it the right to use some degree of physical coercion or threat thereof to effect it ... The "reasonableness" of a particular force must be judged from the perspective of a reasonable officer on the scene, rather than with the 20/20 vision of hindsight. The Fourth Amendment is not violated by an arrest based on probable cause, even though the wrong person is arrested, nor by the mistaken execution of a valid search warrant on the wrong premises. With respect to a claim of excessive force, the same standard of reasonableness at the moment applies."

Writing for the high court, Justice William Rehnquist went on to quote another excessive force case from 1973. "Not every push or shove, even if it may later seem unnecessary, in the peace of a judge's chambers" violates the Constitution, he wrote.