D.C. Circuit Judge Ketanji Brown Jackson would become the first former public defender to serve on the U.S. Supreme Court if confirmed, breathing new life into what some experts say is a neglected area of the high court's docket.

No justice since Thurgood Marshall has approached the depth and breadth of Judge Jackson's criminal law expertise. In addition to representing indigent defendants from 2005 to 2007, she had white collar clients during stints at law firms including Morrison & Foerster LLP. For four years, she served on the commission that sets all-important federal sentencing guidelines. And with nearly a decade presiding over a district court, she would bring more trial judge experience than any of her colleagues.

Judge Jackson, who would be the first Black woman on the court, would also add a defense perspective that many believe is woefully underrepresented in the judiciary.

"People who don't have that perspective think that the criminal justice system is simply a battle between two equally worthy attorneys — each side has its champion," Judge Jed Rakoff of the Southern District of New York told Law360. "But that's not the reality. The reality is that prosecutors have overwhelmingly greater power than the defense."

Justice Marshall wasn't a public defender, but he represented dozens of criminal defendants throughout his career as counsel for the NAACP Legal Defense Fund. Since his retirement in 1991, no justice has had criminal defense experience, but the number of former prosecutors and their collective years of experience have soared.

A justice's background alone doesn't determine how they will vote, and experts say Judge Jackson is a meticulous jurist whose opinions betray no ideological bias. But as former Justice Sandra Day O'Connor noted of Justice Marshall, his experience representing defendants allowed him to reveal what "legal briefs often obscure: the impact of legal rules on human lives."

Defense attorneys also have insight into a role foreign to even the most seasoned judges: the seat opposite prosecutors at the plea bargaining table, where the overwhelming majority of cases are resolved. Judges are barred from the process, and the government wields an enormous advantage, with full access to evidence and leverage from indictable offenses and sentencing guidelines.

"The stakes of a high-level Supreme Court decision will show up in those negotiations, and you need to understand the pressure that defendants are under, the pressure prosecutors are under, the way the bureaucracy unfolds," Brian Richardson, a professor at Cornell University Law School, told Law360. "That is hard-won knowledge, and she has it."

By replacing retiring Justice Stephen Breyer, Judge Jackson wouldn't fundamentally alter the court's ideological balance. But her lifelong focus on criminal justice would diverge sharply from her predecessor's specialty in administrative law.

"There were a number of periods in her life where she woke up every day and all she was thinking about was criminal justice matters. ... Biography isn't destiny, but it provides a sound basis to predict what will be the topics of continuing interest," Douglas A. Berman, a professor at the Ohio State University's Moritz College of Law, told Law360.

And there's no shortage of pressing criminal law questions for the Supreme Court to resolve, a pipeline that's only growing as the justices decide roughly half as many cases as they did in years past. Much of the unsettled law could stem from white collar cases, including long-simmering disputes over the reach of wire fraud, computer crime and foreign bribery statutes.

That could present opportunities for Judge Jackson to lift the criminal docket with the help of the court's conservative members, who have shown willingness to rein in the government's power in recent fraud, corruption and financial enforcement cases.

Some Republicans have criticized Judge Jackson over her representation of Guantanamo Bay prisoners while she was a public defender in D.C. But she won the support of three Republican senators when confirmed to the D.C. Circuit on a 53-44 vote last summer, and she has so far been largely immune to "soft-on-crime" attacks.

Serving as a district judge from 2013 to 2021, Judge Jackson demonstrated that she can deftly balance compassion with public safety. That skill was on display in the prosecution of "Pizzagate" gunman Edgar Maddison Welch, one of her most high-profile criminal cases. 

In 2016, Welch drove 360 miles from his home in North Carolina to Washington, D.C., to investigate a debunked conspiracy theory that a pizza restaurant housed a child prostitution ring catering to Democratic elites. Welch entered the eatery, Comet Ping Pong, brandishing an AR-15 and fired multiple rounds before surrendering to police. He later pled guilty to weapons charges.

Judge Jackson sentenced Welch to four years in prison at a 2017 hearing where the victims shared how the incident marked the terrifying crescendo of a relentless online harassment campaign by conspiracy theorists.

"Mr. Welch, I hope you understand and see how much people are suffering as a result of what you did," Judge Jackson said. "And I also hope that you take away from this, in addition to these heart-wrenching stories about the impact, the fact that this really doesn't happen every day in my courtroom or even in this courthouse."

But she also acknowledged that Welch appeared to be a well-intentioned person who fell down a rabbit hole and lost his grip on reality.

"I believe that you thought that you were being helpful in doing the right thing. You weren't some robber who burst into the restaurant looking for money or trying to benefit yourself personally," she said. "But the problem is that, in our society, no matter how well-intentioned, people are not permitted to take matters into their own hands."

Judge Jackson's eight-year tenure as a district judge surpasses Justice Sonia Sotomayor's five years. Justice Sotomayor is the only sitting justice to have held the title.

Criminal cases generally aren't resolved with written opinions, but experts say Judge Jackson's nearly 600 written rulings in civil cases reflect a mastery of the nitty-gritty — many run longer than 100 pages.

Only 14 of Judge Jackson's opinions have been reversed, though among those was perhaps her most well-known ruling: a 120-page treatise finding that ex-White House Counsel Don McGahn was required to testify as part of a congressional probe into former President Donald Trump. The D.C. Circuit reversed Judge Jackson 2-1, but the full court later reinstated her opinion.

Judge Jackson's tenure on the U.S. Sentencing Commission from 2010 to 2014 also offered a preview of the evenhandedness she would later bring to the bench. In 2011, after Congress moved to shrink the enormous sentencing disparity between crack and powder cocaine offenses — which led to wildly disproportionate sentences for Black defendants — it was left for the commission to decide whether the change would be retroactive.

During a commission meeting, Judge Jackson laid out a tightly reasoned argument for retroactive application, emphasizing that she was no "caricature of a policymaker intent on freeing violent felons." She also appealed to fairness, saying the disparity cast a "long and persistent shadow" that "spawned clouds of controversy and an aura of unfairness that has shrouded nearly every federal crack cocaine sentence."

The commission ultimately voted to make the changes retroactive.

Federal sentencing guidelines themselves cast a long shadow. While the system was designed in the 1980s to eliminate sentencing disparities, it often recommends exorbitant penalties based on arbitrary and outdated metrics, according to a broad consensus of judges, scholars and attorneys.

The technocratic nature of the guidelines can obscure their immense weight for defendants, Richardson noted. But as a defender, sentencing commissioner and longtime judge, Jackson has seen their impact from all angles.

"It's very important to understand the gravity of those choices, and that's difficult to do unless you've spent a lot of time across the table from prosecutors, a lot of time advising clients and a lot of time at the district court level," Richardson said.

--Editing by Alanna Weissman and Kelly Duncan.

Correction: A previous version of this article contained incorrect information about D.C. courts. The error has been corrected.