Gasps emerged from the courtroom as a rare guilty verdict was rendered for white police officer Amber Guyger. Guyger was charged with murder in the fatal shooting of unarmed African American Botham Jean. In an exercise of disturbingly incompetent judgment, Guyger entered the wrong apartment, believed Jean was an intruder, and open fired. He was unarmed, eating a bowl of vanilla ice cream on his couch. According to NBC the case became a painful reminder that when it comes to interactions between Afrcian Americans and the U.S. police force, “law-abiding citizens are not safe even in their own homes.”

This case adds to a long list of police killings targeting African Americans. Recent FBI data notes that African Americans account for 31 percent of police killing victims, while comprising just 13 percent of the population. According to a comprehensive study by experts from Rutgers University’s School of Criminal Justice, Washington University in St. Louis’s Department of Sociology and the University of Michigan’s Institute for Social Research, “in the U.S., African Americans are 2.5 times more likely to be killed by police than white people.”

The shooting took place in Dallas, Texas, a city fraught with racial tensions and a history of racialized violence. This was one of many reasons the conviction came as a shock.

But why is it so surprising that such a clear example of abusive conduct was punished? It’s because both cops and the jury, are told to rationalize lethal force. Two Supreme Court cases – both involving unarmed African Americans – helped legitimize this sentiment and have given police officer’s wide jurisdiction in their ability to kill on sight.

First, the Supreme Court decision in Tennessee v. Garner.

In 1985, police officer Elton Hymon shot and killed 15-year-old Edward Garner. Garner was fleeing a home in Memphis Tennessee, from which he had stolen 10 dollars and a purse. Hymon openly admitted that when he approached Garner, he could see both his hands, and knew he was likely unarmed. However, according to the Memphis Police Department’s policy on deadly force, “If, after notice of the intention to arrest the defendant, he either flee or forcibly resist, the officer may use all the necessary means to effect the arrest." Under the protection of Memphis law, Hymon opened fire as Garner began to flee, piercing the back of his skull.

The case was brought forth by Garner’s father and, in what was initially perceived as a successful effort to decrease police violence, the Supreme Court sided with Garner’s family. The court noted that deadly force could only be used in instances where officers have "probable cause to believe that the suspect poses a threat of serious physical harm, either to the officer or to others."

Unfortunately, it was the vague mention of “probable cause” that has led to so many instances of a confused jury and inevitably, a non-guilty verdict. In fact, “probable cause” was the rationale behind another Supreme Court decision, Graham v. Connor in 1989.

Dethorne Graham was spotted leaving a convenience store in Charlotte, North Carolina. According to the legal report, Officer M.S. Connor believed Graham had left the store “unusually quickly” and in response, pulled him over as he left in a friend’s car. Being a diabetic, Graham was suffering what his friend, William Berry, noted as a “sugar reaction,” causing him to exit the car and soon pass out. As Berry begged law enforcement to check Graham's pocket for a diabetic decal, the officers forced Graham's face down against the hood of the car, and smashed his head into the back of the police car. When Graham regained consciousness, he had suffered “multiple injuries, including a broken foot.”

When this case was seen before the Supreme Court, they ruled in favor of Officer Connor. According to the majority opinion, “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.” In other words, in the United States, by law, it is up to the discretion of the police officer to deem whether or not deadly force is reasonable.

There lies the predicament of the current United States jury.

There is no standard definition of what does and does not constitute a “reasonable” threat to a police officer. Asking ten individuals to come to a unanimous consensus that an officer’s fear was not warranted, is an incredibly difficult task. Rather than asking prosecutors, sociologists or legal experts, the current judicial system forces random individuals to use their personal opinion to decide whether or not the split second decision of a police officer’s gun shot was in response to a warranted threat, from the perception of the officer. According to former prosecutor Katie Phang, “It really leaves it as somewhat of a free for all for a jury to have to make a decision … You and I both have different interpretations of what’s reasonable, we all do, so you’re trying to ask the jurors to come to one unified decision based on their individual interpretations … And that makes almost an impossible standard for the government or the state to be able to achieve.”

While efforts to reduce police brutality including higher diversity on the police force, body cameras with public access to footage and racial consciousness training are all noble initiatives in reducing police misconduct, none combat the deeply troubled U.S legal system. As of now, only in cases such as Amy Guyger’s, where the facts of the case are so inarguably apparent of unnecessary force, can a jury collectively deliver a guilty verdict.

Unless the U.S. legal system gets some kind of universal overhaul, don’t expect many more guilty verdicts for white police officers, even if their victims are unarmed and their crimes are caught on tape.