It was springtime in Baltimore when 25-year-old Freddie Gray, arrested for alleged possession of a switchblade (it turned out to be a legal pocketknife), died after being injured in police custody and the city’s black residents reached their breaking point. The “Baltimore Uprising,” the two-week-long protests that followed in Gray’s neighborhood, was sparked by a confluence of many factors. There was, of course, the unending barrage of high-profile deaths of black men across the country—Eric Garner in New York City and Michael Brown in Ferguson, Missouri, in 2014, and Walter Scott in South Carolina just a few days before Freddie Gray. It was, due, too, to a long-simmering tension between Baltimore’s black residents and the police. A Department of Justice report released in August 2016 found that it was common for police to chase after Baltimore residents, as they did with Gray, and concluded that the department engaged in discriminatory policing, targeting black residents for low-level offenses. A decade earlier, in 2006, the Maryland chapters of the ACLU and NAACP sued the police for making illegal arrests. But perhaps the most significant driver of the anger that bubbled over into the streets was the realization that the indiscriminate killing of black men in America by police wasn’t yielding convictions of police officers. Many times, it wasn’t even yielding an indictment.

By the time Freddie Gray was killed, Black America had already reckoned with the fact that Darren Wilson wouldn’t even go to trial for killing Michael Brown. The same was true for the cops who were involved in the death of Eric Garner. And Baltimore reacted.

But then something extraordinary happened. “I have heard your calls for ‘no justice, no peace!’” the city’s newly elected prosecutor, Marilyn Mosby, declared at a press conference almost two weeks after Gray’s death. Days after Gray’s funeral, she did something that almost no other prosecutor in a comparable case had done: She brought charges against the cops involved in his death. To many who were cynical about cops’ getting off too easily, it brought a much-needed sigh of relief, and a little faith. Suddenly Mosby was being held up among liberals as a prosecutor who was holding police accountable. Despite her words of reassurance to police officers—“To the rank-and-file officers of the Baltimore city police department, please know that these accusations of these six officers are not an indictment on the entire force”—she became reviled among cops and conservatives.

But Mosby’s tenure as the left’s new darling was short-lived. She successfully brought six officers to trial, but judges cleared three of charges. After that, Mosby dropped charges against the remaining three. In a July 2016 news conference announcing the dropped charges, Mosby said, “Without real, substantive reforms to the current criminal-justice system we could try this case 100 times, and cases just like it, and we would still end up with the same result.” Having an independent agency investigate from the start, and a say over whether the case would proceed before a judge or jury, would have changed the outcome, Mosby suggested. An account of her epic fall from grace in The New York Times Magazine hinted at the biggest challenge for a self-proclaimed progressive state’s attorney, and a Baltimore Sun article put it bluntly: “The [Freddie Gray] case pitted Mosby against police.”

There is a tension, one that may be unresolvable, between prosecutors who want to make substantive reforms to the criminal-justice system—like ending mandatory minimums, overturning wrongful convictions, reforming cash bail, limiting or ending the use of the death penalty, and creating diversionary programs for drug offenses—and the reality of the prosecutor’s role within the criminal-justice system. It is a conflict of interest to have prosecutors—as civil-rights attorney James Meyerson, who’s also my father, wrote for The Huffington Post—tasked with investigating and charging police for crimes committed against citizens. Most of the time, prosecutors, who are simply trying to get convictions, are working with police to bring charges against civilians. Police are the eyes and ears of a prosecutor’s office. Prosecutors rely on police investigators to bring cases against civilians, to show up in court and testify as witnesses, and to extract confessions from suspects. So how can they be expected to go against their own when it comes to charging their friends with police misconduct? Some cities have appointed special prosecutors to investigate police killings, and the state of New York recently tried to address this conundrum by creating a special prosecutor’s office specifically to investigate police-involved deaths of civilians. But this tension raises a larger question: Is it possible for a prosecutor to reform a broken criminal-justice system when they have to work so closely with, and rely on, law enforcement to do so much of their job?

“We’re only now venturing into territory where I would even remotely call a prosecutor progressive, and I’m not even sure if a progressive prosecutor is a possibility anyway,” Fair Punishment Project’s Josie Duffy Rice tells me. “It may not even be a useful term, because the job itself is so fundamentally not progressive. At its most essential, the job is punishment, and given the systemic limitations, there isn’t a prosecutor in America who isn’t locking up too many poor people of color.”

In her desire to bring a different approach to the prosecutor’s office, Marilyn Mosby is not alone. Recently, a rash of self-proclaimed progressive prosecutors have made public moves toward reform. There’s Aramis Ayala, who promised not to seek the death penalty in Orlando. Scott Colom, in eastern Mississippi, has stopped prosecuting low-level drug offenses. Kim Foxx, the first black woman DA in Chicago, promised to create a unit focused on gun trafficking.

And there are more coming. In Philadelphia, longtime civil rights attorney Larry Krasner, who has sued police more than 75 times in his career, is promising to reform harsh sentencing and eradicate money bail. He was elected district attorney on November 8. Geneviéve Jones-Wright, a black deputy public defender and lifelong native of San Diego, is seeking to beat a Republican district attorney who has been endorsed by the law-enforcement community, as well as some establishment Democrats. “I believe the DA’s office needs to be more justice-minded and oriented, rather than being conviction rate-minded,” she told The San Diego Union Tribune.

It’s already clear that Republicans in the states where progressive prosecutors win are going to do their best to stymie their attempts at reform. Ayala, who won the state’s attorney election last year in Orlando, vowed to stop seeking the death penalty, citing evidence that capital punishment does not work as a deterrent. After she made her announcement, Florida’s Republican governor, Rick Scott, issued an executive order removing her from all capital murder cases, including one in which a police officer was killed because, he said, Ayala “made it clear that she will not fight for justice.” In September, after the governor came out against her, Ayala rescinded her promise to not to seek the death penalty and created a panel made up of assistant state’s attorneys will decide whether or not to pursue capital punishment in all first-degree capital murder cases.

Republicans aren’t the only foes of reform once prosecutors get into office. A prosecutor who found a “progressive” message useful during campaign season may jettison it once in office. As Rice pointed out in an op-ed for The New York Times last month, a prosecutor can talk the talk without walking the walk. Manhattan District Attorney Cyrus Vance Jr. “is considered one of America’s most progressive prosecutors and has the accolades to prove it.” But with more than 40 percent of inmates languishing in Rikers Island coming from Manhattan, which has only 20 percent of New York City’s population, it’s clear that Vance’s public image and priorities on the job are in conflict.

Rice is waiting to see what self-described “progressive” prosecutors who have been elected more recently do once in office. “The real ‘progressive’ prosecutors, like Kim Foxx, Kim Gardner, and hopefully Larry Krasner, have been in office a year or less,” she points out. So, she says, it’s hard to quantify their success this early on.

Many of these newly elected prosecutors, like Ayala, who are seeking to bring reform to red and purple states, are pushing back against the death penalty. Back in February, the New York Times editorial board hailed this as progress, describing these DAs as a “wiser generation of prosecutors.” There’s James Stewart, who according to The Christian Science Monitor, has “quietly” avoided the death penalty in Caddo Parish, Louisiana, which has the highest incarceration rate in the country. Denver’s first female prosecutor, Beth McCann, who took office in January, has sworn not to pursue death-penalty cases. Kim Ogg in Houston, Texas, also ran on an anti–death penalty platform and won. But when it comes to being tough on police, and other criminal-justice reforms, there are big question marks. Different cities call for different kinds of reform, and, as Trump continues to impose his agenda, the needs of every county will come into clearer focus.

It is too soon to tell whether these reform prosecutors will deliver, but one thing is not in question: Many voters are no longer interested in the “tough on crime” stances of the past.

Jake Bittle contributed to this reporting.