Police sometimes see things differently.

Former Ferguson Police Officer Darren Wilson told a grand jury that Michael Brown looked like a “demon” who might shrug off a hail of bullets before Wilson shot him dead. Shortly after Cleveland Police Officer Timothy Loehmann gunned down Tamir Rice, a 12-year-old holding a toy gun, he told the dispatcher that Rice, who was shot within two seconds of Loehmann’s arrival, was “maybe 20.” Milwaukee Police Officer Christopher Manney told investigators that Dontre Hamilton, an unarmed man whom he shot 14 times in October, was so “big” and “muscular” that “he would be impossible to control if you were one-man.” At 5-foot-7 and 180 pounds, Hamilton was below average height and overweight.

Wilson, Loehmann, and Manney are white, and Brown, Rice, and Hamilton were black. They were also unarmed. But in the eyes of the men who killed them, they were frightening enough to provoke the use of lethal force.

These lingering, sometimes unconscious biases help explain why police encounters with black men are so much more likely to end fatally. But it’s not only the perceptions of police that matter. Even after the fact, the American legal system consistently judges these decisions as reasonable, even when there is seemingly incontrovertible evidence that police acted irresponsibly.

On Wednesday, a grand jury declined to indict Daniel Pantaleo, the white Staten Island police officer with a past record of race-related misconduct who was caught on video putting Eric Garner in a chokehold that lead to Garner’s death during an arrest for selling loose cigarettes. On the video, which went viral, Garner can be heard yelling “I can’t breathe” over and over. Chokeholds have been banned by the New York Police Department for 20 years, and the coroner ruled Garner’s death a homicide. But as in Ferguson, the grand jury decided that no crime worth punishing had been committed. We don’t know what Pantaleo said to the grand jury, or why they let him off. But since killing an unarmed suspect is so rarely treated as a crime, there’s little reason for police to believe that it should be.

Police are empowered to use lethal force under certain circumstances, and sometimes, they have to. The Supreme Court has held that police can use lethal force if they have a “reasonable belief” they are facing danger or if a fleeing suspect poses a danger to others. But it’s not just the beliefs of police that matter. It is also the beliefs of the citizens empowered to evaluate their decisions after the fact. And Americans almost always decide that police use of lethal force is reasonable. Given the fact that blacks are several times more likely than whites to be killed by police, that inevitably means that it’s often the deaths of black men that are deemed justified.

It is difficult to know how many people are killed by police each year, because despite police and their advocates’ affinity for the phrase “data-driven policing,” how many times police kill people is data they simply haven’t gotten around to properly gathering yet.

Police sometimes kill unarmed white men, like Dillon Taylor in Utah. But the flawed data we have shows police kill white people far less often than they kill black people relative to their proportion of the population. That white men are also harmed by a system that disproportionately allows black men to be killed with impunity does not exonerate the system.

This has something to do with the way police see things. Police are people, after all, subject to the same flaws and vices as the rest of us. America’s police departments tend to be whiter than the general population, and nearly half of whites believe “many” or “almost all” black men are violent. Whites overestimate the amount of crime, in particular violent crime, involving blacks. Whites are also more likely to ascribe supernatural physical abilities to black people, in particular the ability to resist physical pain, a stereotype that harkens back to slavery. Black children like Tamir Rice are “more likely to be mistaken as older, be perceived as guilty and face police violence if accused of a crime.”

“Reasonable,” of course, is a subjective standard — even as a legal definition. Civil society decides what “reasonable” means, and when citizens make that decision, they almost always side with the police, even when the deceased is white. But when society weighs whether the deaths of black men at the hands of police are reasonable, it does so with the additional burden of American beliefs about black criminality, black superstrength, black dangerousness. On the other side are our collective beliefs about police, seen as more noble, more selfless, and more resistant to all-too-human flaws like wrath or deceit.

Small wonder, then, that the scales of justice are so often unbalanced.