On April 20, a jury found former Minnesota police officer Derek Chauvin guilty of all three charges brought against him: second-degree murder, third-degree murder, and second-degree manslaughter. The prosecution called witnesses who had watched as Chauvin knelt on George Floyd’s neck for more than eight and a half minutes; doctors who argued that Floyd’s death was a direct result of Chauvin’s actions; and police officers, including the Minneapolis chief of police, who confirmed that Chauvin’s actions went well beyond any reasonable use of force.

Defense attorney Eric Nelson said he wanted to “contextualize” Floyd’s death, introducing other possible causes of death that were subsequently rejected by medical experts called by the prosecution. Nelson also argued that Chauvin’s use of force had been justified and that he had been too distracted by bystanders to provide Floyd with care. But in fact those bystanders had been calling for Chauvin to remove his knee from Floyd’s neck and check his pulse. In the awful video of that day’s events, Chauvin does not look distracted; he looks indifferent.

But Nelson is right that we should understand the context for Floyd’s death. That means recognizing that it fits into a larger pattern of police violence, most of which goes unpunished. Chauvin’s case is a rare, highly publicized exception: his actions were clearly recorded for a period of agonizing minutes, not a few blurred seconds, and condemned, rather than defended, by the local police department. Though police kill more than 900 people a year, a fourteen-year study of officer arrests found only 104 cases where officers were charged with manslaughter or murder—and these resulted in only thirty-five convictions. Police unions negotiate contracts that make it exceedingly difficult to hold officers accountable. Such contracts correlate with an increase in use-of-force incidents, particularly against people of color. Protections like qualified immunity and an extremely high standard of intent at the federal level make it similarly difficult to prosecute. And prosecutors, who rely on police cooperation in their other cases, are sometimes hesitant to damage relationships with police departments and unions by bringing cases against officers. As a result, the police are too often left to police themselves. When Minnesota’s civilian review board was replaced by an officer board in 2012, only twelve of more than 2,600 complaints incurred any punishments, the most severe of which was a forty-hour suspension. Chauvin himself was the subject of eighteen misconduct complaints before he killed Floyd. The result? Two letters of reprimand.

Federal investigations around the country provide further context for what happened to Floyd. They have found not only a lack of accountability, but also a culture within many police departments that pits officers against the communities they are supposed to protect. Too many police training programs still encourage excessively combative responses rather than de-escalation. Too many departments reward officers according to the number of arrests they make, even for minor and nonviolent infractions such as passing counterfeit bills (as in Floyd’s case) or driving with expired plates (as in Daunte Wright’s). These problems disproportionately affect Black Americans, whose communities are more likely to be victims of “broken windows” policing, and who are arrested and killed at more than twice the rate of white Americans.

Some cities are enacting police reforms in the wake of last summer’s protests. Unfortunately, many of these reforms seek to treat individual symptoms of the problem (e.g., by banning chokeholds or mandating one-time racial-bias training) without addressing the perverse incentive structure that encourages police to err on the side of excessive force. But the culture of impunity that led to Floyd’s death won’t change until there are serious consequences not just for Chauvin, but for any officer whose abuse of power results in an unnecessary death.