Last year, the Innocence Project helped exonerate nine people who had served a combined 200 years in prison. Some of the cases seemed to be built on strong evidence. A detective claimed Keith Hardin made incriminating statements. A forensic dentist testified that Alfred Swinton was responsible for bite marks left on a murder victim. An eyewitness stated that he saw Johnny Tall Bear beating a man to death. Eric Kelley and Kevin Bailey both confessed. But DNA testing helped clear all of them.

Even the most convincing evidence passes through a criminal-justice system that is tainted by biases, emotions, and errors. The result is a profusion of injustices: wrongful convictions, racial discrimination, overlooked or dismissed evidence, abuses of power, unwarranted police shootings. No amount of reform, perhaps, can wholly eradicate the faulty human element from law-enforcement agencies or courtrooms. But by making discrete, practical policy changes, police officers and prosecutors could change the structures that support and entrench those injustices.

Jennifer Eberhardt, a Stanford psychology professor and the author of Biased: Uncovering the Hidden Prejudice That Shapes What We See, Think, and Do, has done extensive research into racial bias in law enforcement. In a conversation Thursday at the Aspen Ideas Festival, which is co-hosted by the Aspen Institute and The Atlantic, she said she’s found that police officers have a “black-crime association” that can shape the way cases move through the criminal-justice system.

In an attempt to combat that bias, Eberhardt has worked with law-enforcement agencies to introduce practical reforms that will combat prejudice before it builds into narratives and, maybe, unjust outcomes. “One of the ways to correct these biases is not simply through a bias training or something,” she said. “It’s trying to understand what practices or what policies might be driving the disparity.”

[Read: Can cops unlearn their unconscious biases?]

To counteract eyewitness misidentification, for instance, she said she has encouraged police officers to change the way they show lineups to witnesses. By explicitly telling witnesses that the perpetrator may not be present and by introducing each member of the lineup individually, she found that officers could deter witnesses from feeling like they should just pick whoever looked the most like the person they saw. She has also worked to change policies that required officers to handcuff anyone they stopped who was on probation or parole—policies that led to a disproportionate number of black men being restrained.

Practical reforms can also combat prejudice in prosecutors’ offices. For example, in the past four decades, some state and local governments have targeted “blindfold laws,” which still allow district attorneys to indefinitely withhold information like the names and statements of witnesses from defense teams in nine states. “Open file” laws, which require prosecutors to share that evidence well before trial, have replaced them. New York State changed its policy in May.

Such changes introduce “a different set of defaults that guard against the biases and against this tremendous power that people in law enforcement have,” said Emily Bazelon, a staff writer for The New York Times Magazine and the author of Charged: The New Movement to Transform American Prosecution and End Mass Incarceration, in conversation with Eberhardt on Thursday.

[Read: The bias in Fresno’s justice system]

Bazelon said that challenging the power of prosecutors is especially significant because, legally, they have absolute immunity for the decisions they make on the job and cannot be sued for mishandling cases. (Police officers have qualified immunity, which allows them to face lawsuits only for professional actions that violate “clearly established” federal laws or rights.)

“People who wield huge amounts of power have to have checks on that power, and we seem to have forgotten that lesson in the realm of prosecutors,” Bazelon said.

Prosecutors, she said, have been resistant to reforms like open-file laws that would introduce more transparency to their jobs. “Sometimes we see these human tendencies [toward prejudice and confirmation bias] reinforced by another tendency, which is people’s faith in the status quo,” Bazelon said. “You’ve done it one way for a long time, and that must be the way that you have to do it.”

But since 2016, she observed, voters in several big cities have elected progressive district attorneys to disrupt that status quo—to reduce incarceration, combat racial discrimination, and build a more just and equitable prosecutorial mold. Those new incentives could adjust the mind-sets prosecutors bring into their offices. And in doing so, maybe they could change the court system for the better.