According to Vox, Booker, a Democratic senator from New Jersey, has supported extensive criminal justice reforms at the federal, state, and local levels. The outlet noted that, like many of his fellow legislators in Congress, Booker supported the First Step Act, the recently-passed bipartisan legislation to reform the federal prison system through sentencing reforms and improving in-prison care. Indeed, as the senator described on his website, he sponsored the Senate version of the act and was crucial in ensuring that sentencing reforms — not just prison reforms — were included in the bill.

According to Vox, one of these reforms included the the relaxing of mandatory minimum sentencing requirements — requirements which sometimes resulted in nonviolent offenders being sentenced to life in prison. Another reform consisted of changes to end the inconsistency between crack and powder cocaine sentences, which often saw those with crack cocaine convictions receive much longer sentences. Beyond sentencing reforms, Booker also ensured that his Mercy Act, which prohibits juvenile solitary confinement in federal facilities, was included in the bill, the Juvenile Law Center reported.

In addition to his work on the First Step Act, some other criminal justice reform legislation that Booker has recently sponsored (but that have not yet passed Congress) include:

• The Reverse Mass Incarceration Act: a bill which, as Vox reported, awards money to states that reduce their prison populations but also keep crime rates low.
• Marijuana legalization bill: a bill that removes marijuana from the federal list of illegal drugs, which would also likely lower the number of people in prison for drug crimes, Green Entrepreneur reported.

Notably, Booker's website also includes a lengthy list of additional criminal justice proposals that he's introduced over the past five years.

Harris is a Democratic senator from California and a former prosecutor. As a senator, she has advocated for multiple criminal justice reform initiatives, The Independent reported. Though, as a candidate, she has received some pushback because of her work as a prosecutor, Vox noted.

As Vox explained, Harris' record as a prosecutor is a bit contradictory in regard to criminal justice reform. For example, the outlet noted that, as a prosecutor, she pushed for programs that gave people jobs instead of incarcerating them. However, the outlet added that her office also pushed to keep an individual in prison who had been found innocent. As NBC 4 explained, in 2009 a man named Daniel Larsen had his concealed weapon conviction overturned, with the Innocence Project reporting that a California court found that he was "innocent, the police officers who testified at his trial were not credible, and his trial attorney was constitutionally ineffective."

However, Larsen wasn't released from prison until 2013. Up until that time, Harris' office had appealed his release on what many viewed as a technicality, saying his lawyers hadn't filed his release paperwork on time, the Los Angeles Times reported.

When asked if she had any regrets from her time as a prosecutor, Harris said during a campaign event on Jan. 21 (via Vox), “The bottom line is the buck stops with me and I take full responsibility for what my office did ... There are cases ... where there were folks that made a decision in my office and they had not consulted me and I wish they had.”

As a senator, Harris has been quite active in criminal justice reform. For example, she similarly helped push for sentencing reforms to be included in the First Step Act, The Independent reported. Moreover, she has worked extensively with The Sentencing Project, a nonprofit, to help push for reforms to reduce mass incarceration and mandatory minimum sentencing, the outlet noted.

Like many of her Democratic colleagues, Senator Kirsten Gillibrand of New York also supported the First Step Act. Notably, like many others, she asserted that she doesn't believe the bill goes far enough to make changes to the federal criminal justice system, the New York Daily News reported. Specifically, the paper noted that she believes the legislation should've reformed the cash bail system — a criminal justice reform issue about which Gillibrand is particularly passionate.

Indeed, in December 2018 Gillibrand released a statement on her website calling on Congress to make changes to the cash bail system, which can sometimes keep people who haven't been charged with a crime in jail for months if they can't afford to bail out. Gillibrand is a co-sponsor of the No Money Bail Act, which heavily promotes alternative methods to cash bail. The bill has not yet passed Congress.

In the past, Gillibrand has also advocated for other criminal justice reform measures. For example, as the Watertown Daily Times reported, she's repeatedly introduced the Military Justice Improvement Act bill, which would permit military prosecutors to handle military sexual assault cases as opposed to military leadership.

Gabbard currently serves as a Democratic U.S. representative from Hawaii. Her campaign website indicates that she is committed to criminal justice reform. Specifically, the site reveals that Gabbard is "working to reduce mandatory minimums for certain non-violent offenders, recidivism rates, crime rates, and the social and economic cost of an over-criminalized society."

Moreover, as a representative in Congress, she co-sponsored the First Step Act. Her government website indicates that Gabbard also introduced the Ending Federal Marijuana Prohibition Act, and co-sponsored ongoing sentencing reform bills, like the SAFE Justice Act and the Sentencing Reform Act. The SAFE Justice Act introduces criminal justice reforms used by some states into the federal system, such as pursuing additional alternatives to detention and reducing recidivism through giving inmates incentives to receive earned time. The Sentencing Reform Act gives judges more discretion in federal sentencing and diminishes mandatory minimum sentences for some non-violent criminals.

Klobuchar is a Democratic senator from Minnesota as well as a former prosecutor in the state's Hennepin County. As a legislator, she has supported bipartisan criminal justice reform initiatives and has co-sponsored the First Step Act.

"As a former prosecutor, I know firsthand that our criminal justice system must ensure the fair administration of justice while keeping our communities safe,” she asserted during a speech on the Senate floor to advocate for the bill (via her website). “This bipartisan legislation makes needed changes to our sentencing laws, while also bringing important reforms to federal prisons."

However, as Vox reported, Klobuchar has also been known for being tough on crime, particularly during her years as a prosecutor. As the outlet described, while she was a prosecutor from 1999 to 2007, she advocated for policies that are seemingly the antithesis of the modern criminal justice reform movement. The outlet noted that these policies included longer sentences for nonviolent and repeat offenders and harsher penalties for drug offenders.

Sanders, an Independent senator from Vermont, has extensively advocated for criminal justice reform as a lawmaker. In recent years, The Intercept reported that the senator has been highly committed to ending the criminalization of poverty, the notion that those with less money are more likely to face incarceration and re-incarceration. As the outlet noted, after spending time engaging with criminal justice reform activists in the African American community, Sanders indicated that he is much more aware of and committed to ending the racial and economic disparities in the criminal justice system.

"Our country is basically criminalizing poverty. I’ll be honest with you. I really didn’t know this was happening," Sanders told The Intercept in June 2018. "I had no idea hundreds of thousands of Americans, particularly African-Americans, were being held in jail, for months or years, even though they’ve never been convicted of a crime, simply because they can’t afford bail. I see the racial disparities clearer than ever. I want to help."

One of the ways Sanders has sought to address this issue is through introducing the aforementioned No Money Bail Act to prevent money from dictating who spends time in jail.

As both a Democratic senator and presidential candidate, Warren has repeatedly stressed that she believes the United States needs extensive criminal justice reforms, particularly when it comes to addressing racial disparities in the criminal justice system.

On her campaign website, Warren stresses she's advocating for equal justice under the law. "It’s not equal justice when, for the exact same crimes, African Americans are more likely than whites to be arrested, more likely to be charged, more likely to be convicted, and more likely to be sentenced," Warren's website notes.

Her campaign website also reveals that she's committed to banning private prisons, demilitarizing police forces, relying on community policing, decriminalizing marijuana, and reforming sentencing guidelines in order to improve the criminal justice system. Some of Warren's work as a senator, including her support of the First Step Act and her support for marijuana decriminalization, reflect these initiatives, the Boston Globe reported.

Castro, a Democrat, was a former mayor of San Antonio, Texas, as well as the secretary of housing and urban development under President Barack Obama. On the campaign trail, he has been very outspoken about the need for criminal justice reform.

For example, KSAT 12, an ABC affiliate, reported that, at an event announcing his presidential run on Jan. 12, Castro said that he plans to make criminal justice reform a key tenant of his campaign. “To be the fairest nation, we have to reform and reimagine our justice system," Castro at the event (via KSAT 12). "All over this nation, for far too many people of color, any interaction with the police can become fatal."

On his campaign website, Castro asserts that "addressing police violence in communities of color" is one of his biggest priorities. He also noted that he wants to create "a reimagined justice system that treats all people, regardless of who they are or where they come from, with fairness."

Democrat Buttigieg is currently the mayor of South Bend, Indiana. While he hasn't provided a great deal of specifics about criminal justice reform on his campaign website, he's emphasized to the press that he considers the issue incredibly important. For example, as the mayor told Out in February 2019:

I consider criminal justice reform to be a key issue. The cost of incarceration — and I’m not just saying the fiscal cost, but the social cost of incarceration — is tremendous. It’s clearly worsening some of the patterns of racial inequality in our country, too. I think more Americans than we realize agree on this issue. We just need more politicians to catch up.

Delaney formerly served as a Democratic representative for Maryland. On his campaign website, he lists reforming America's "immoral criminal justice system" as one of his priorities. Moreover, during a December 2018 interview on CNBC, Delaney said that one of the first things he wants to do as president is "fix our broken immigration and criminal justice systems."

In January, Delaney also released a statement on his website supporting recent criminal justice reforms, like the restoration of ex-felons' voting rights in Florida. “The restoration of voting rights for ex-felons shows again the power of understanding and empathy," Delaney said on his campaign website. "Those who have served their time should be encouraged and supported upon their release, including job training and placement, assistance finding a home and re-building the stabilizing roots of a productive life."

As governor of Washington, Jay Inslee, a Democrat, has signed several pieces of legislation to promote comprehensive criminal justice reforms in the state. For example, in June 2018, the governor revealed on his website that he signed a package of bills related to juvenile justice reform. These bills mandated a host of changes regarding youth incarceration. They included ending rules in Washington that required automatically trying a minor as an adult for certain crimes, increasing the age at which juvenile offenders are transferred to an adult prison from 21 to 25, and permitting the destruction of juvenile court records, among other changes.

Outside of prison reform, Inslee has also heavily advocated for the decriminalization of marijuana. As his website indicates, he launched the Marijuana Justice Initiative in January, a project which involves him granting clemency to people in Washington who have a misdemeanor marijuana possession charge on their record. As the governor's website describes, this program was designed to "allow people to move on with their lives" and it reflects one step toward "correcting injustices that disproportionately affected communities of color." It is also in line with the state's views on marijuana, as Washington legalized adult recreational use of marijuana in 2012, the governor's website noted.

John Hickenlooper was the Democratic governor of Colorado from January 2011 to January 2019. During his tenure as governor, Hickenlooper signed criminal justice reform bills into law and launched related initiatives. For example, Denver's 9 News, an NBC affiliate, reported in April 2018 that Hickenlooper signed legislation banning the practice of secretly transferring prisoners in Colorado to facilities in other states and not providing victims of their crimes with information about their transfers.

In May 2018, Hickenlooper announced that Colorado would engage in a comprehensive review of its juvenile justice system as a means of promoting youth rehabilitation, the Council of State Governors reported. “Kids don’t belong in prison. We know from the data that when children are incarcerated they usually become repeat offenders again and again,” Hickenlooper said in a statement on the council's website. “This data-driven review will help us provide youths the best chance to successfully transition to a crime-free, productive adulthood.”

Moreover, in 2017, Hickenlooper participated in the Face to Face initiative with several other governors across the country, the National Reentry Resource Center reported. The initiative encouraged governors to visit correctional facilities in their states as a means of promoting criminal justice reform.

However, Hickenlooper has also received some pushback from lawmakers in his state because of his administration's willingness to use private prisons to address prison overcrowding in Colorado. For example, in March 2018, the Colorado Independent reported that Hickenlooper's administration wanted to reopen a closed private prison in Huerfano, Colordado, but many state lawmakers were strongly opposed to the idea. Colorado's Joint Budget Committee decided in June 2018 that the prison would remain closed, the Pueblo Chieftain reported.

Williamson is an author who writes about spirituality and who is most well-known for being Oprah's spiritual adviser, Vox reported. She is running as an Independent candidate. Her campaign website refers to the current political justice system in the United States as a "political and moral disaster."

Williamson proposes several comprehensive criminal justice reforms on her website. She suggests promoting restorative justice programs that "bring healing to victims and communities" as opposed to focusing only on punitive measures. Relatedly, she advocates for trauma-informed justice and courts so those who are incarcerated can receive comprehensive mental health services. She also heavily advocates for strong prisoner rehabilitation and society reentry programs.

O'Rourke, a former Democratic congressman, revealed his strong commitment to criminal justice reform during his (ultimately unsuccessful) bid for the U.S. Senate in 2018. For example, O'Rourke wrote an op-ed in the Houston Chronicle in August 2018 describing how he would reform Texas' criminal justice system. In this op-ed, O'Rourke proposed eliminating private, for-profit prison systems in the state, stopping the use of mandatory minimum sentencing, improving reentry programs for people who have served their sentences, putting an end to oppressive bail bonds, and ending the war on drugs through decriminalizing marijuana.

Yang is an entrepreneur who founded Venture for America, a nonprofit organization. He is running as a Democrat. Yang's campaign website indicates that he is committed to ending mass incarceration and keeping more Americans out of jail. He suggests banning the use of private prisons, reforming drug policy to be more rehabilitation-oriented, and focusing on overall poverty reduction as some ways of achieving this objective.

Yang explains why he believes it's important to reduce mass incarceration in a brief on his website:

America imprisons a higher percentage of its citizens than almost any other country in the world, and minorities are disproportionately represented in this group. Incarceration doesn’t just set someone back for the time they’re imprisoned; with our current felony laws, they follow someone throughout their life. ... While individuals should be punished for committing crimes, the end goal should be to prevent people from committing crimes, and to lower recidivism rates for those who are convicted.

Democratic Ohio Congressman Ryan's congressional website emphasizes that he believes the American prison system is overcrowded and housing many people who are serving overly-long sentences.

As Ryan described online:

The United States has five percent of the world’s population, but 25 percent of the world’s prison population. Many of these offenders have untreated mental health and substance abuse issues. In fact, the three largest mental health providers in our nation are jails. Our federal prisons are overcrowded with 2.2 million men and women, many of whom are serving long mandatory sentences for low-level, nonviolent drug offenses. The cost of detaining a person for one year is $30,000 ... In its current form, our criminal justice system is simply unsustainable.

Messam is the mayor of Miramar, Florida, who is running as a Democrat. Messam reports on the criminal justice section of his website that his city previously passed a "Ban the Box" law. As the Ban the Box campaign explains, this law prohibits employers from asking job applicants whether they have ever been convicted of a crime, allowing formerly incarcerated individuals a better chance of securing a job.

Messam also stresses on his 2020 website that he would be committed to supporting states that choose to legalize marijuana if he's elected president. "[The drug war] has ruined thousands of lives, especially in communities of color," Messam's website notes.

Swalwell, a Democratic congressman from California, doesn't appear to have put forward a comprehensive criminal justice reform plan. The public safety section of the congressman's website indicates he's highly committed to judicial and law enforcement reforms to ensure that victims of crimes receive justice more quickly. Swalwell also notes on his congressional website that, in 2016, he "convened a discussion on juvenile justice and how to break the cycle of poverty and crime ... at the Alameda County Juvenile Court and detention facility in San Leandro."

According to The Washington Post, Swalwell's family has a history in law enforcement careers.

Moulton, a Democratic representative from Massachusetts, doesn't appear to have a section of his campaign website dedicated to criminal justice reform, though he has been supportive of criminal justice reform initiatives in the past. For example, he has publicly advocated for the decriminalization of marijuana, often citing the disproportionate and unjust impact that marijuana arrests have on minorities, Marijuana Moment reported.

"I support legalization, but we do need to make sure it’s done right, and there are very legitimate concerns being brought up by the other side here," Moulton during an interview with WGBH’s Boston Public Radio in 2016. "But here’s the reality. Let’s not kid ourselves. People are using marijuana. They’re using it in America, they’re using it in Massachusetts, and we have an obligation to regulate it and make it as safe as possible."

In terms of other criminal justice reform issues, Moulton has indicated that he supports restoring Americans' voting rights when they are released from prison, but doesn't support allowing prisoners convicted of felonies to vote. "My position would be that people in prison don't vote, but when you get out, then absolutely you should have those rights restored," Moulton said at an April 2019 press gathering, per The Hill. "And we do have a problem in the United States with people who come out of prison and don't get their full rights."

Bullock, the Democratic governor of Montana, has had a somewhat mixed record on criminal justice reform while serving in his current role. For example, in 2017 he signed a package of 10 criminal justice reform bills in Montana, which were designed to improve the state's prison facilities as well as reduce the number of people who ultimately go to prison.

However, Bullock also received criticism, including from the American Civil Liberties Union, for renewing a contract for Montana's only for-profit prison, the CoreCivic Crossroads Correctional Center, back in July 2018. "The contract is an enormous step backward for criminal justice reform in Montana," the ACLU said at the time, per the Great Falls Tribune. The outlet also noted the governor cited budgetary savings plus a much shorter contract renewal (two years versus 10 years) as two of the drivers behind his decision.

Bennet, a Democratic senator from Colorado, has engaged in a host of criminal justice reform initiatives during his time in office. For example, Bennet's Senate website indicates that he advocated for 2017 legislation to help diminish the national rape kit backlog. The senator also supports the legalization of marijuana, his Senate website reveals.

Moreover, Bennet's website notes that he wants to work to reduce the disproportionately negative impact that the criminal justice system has on minorities. As the website describes:

Michael also supports efforts to reform our criminal justice system, which disproportionately affects people of color across the country, by reducing mandatory minimum sentences for low-level offenses and increasing resources for individuals reentering their communities.

As the Washington Post reported, Joe Biden, a former senator and vice president, has a somewhat controversial criminal justice record. The paper noted that, as a senator, Biden helped pass several bills that increased the length of sentences for drug offenders, especially for drugs that were more frequently used by minorities. As the paper described, the passage of these bills helped contribute to a massive increase in incarceration in the United States, something that particularly impacted people of color.

Biden has suggested that his views on criminal justice have changed since the 1990s, when he advocated for the aforementioned legislation. As CNN noted in January 2019, the former vice president emphasized during a speech that he worked with President Obama to reduce sentencing disparities between crack and powder cocaine users. "It was a big mistake when it [the sentencing law] was made," he said, per CNN. "We thought, we were told by the experts, that crack you never go back, it was somehow fundamentally different. It's not different. But it's trapped an entire generation."

Weld, a former Massachusetts governor, is the first Republican to announce his intention to challengeTrump for the party's 2020 nomination. While he was known for being "tough on crime" as governor, he has changed his views about criminal justice reform in recent years, WBUR reported. As Weld told the outlet:

I think the United States is undergoing a reexamination of that [the tough on crime mentality]. You’ll notice in Massachusetts we’ve stopped sending [drug offenders] into Framingham, which is incarceration; we send them somewhere else. And I’m totally behind that. And you would not have gotten that out of my mouth in the late '80s.

Boston.com also reported Weld said in a Feb. 15 speech that he hopes to take criminal justice reforms beyond what was accomplished by the First Step Act. "We should also move on to bail reform, funding for reentry programs, and other criminal justice reforms not reached by the recent First Step legislation," he said via the outlet.

President Donald Trump has a somewhat mixed record on criminal justice reform.

Throughout his presidential campaign and early presidency, he advocated for some policies that generally lie counter to criminal justice reform. For example, as recently as October, Trump said he wanted Chicago police to use stop and frisk tactics to reduce crime in the city, the Washington Post reported. Stop and frisk involves police randomly stopping and searching people if they suspect them of having committed a crime — and the policy typically disproportionately targets people of color, the ACLU of Massachusetts reported. NPR also noted that, in the past, Trump has repeatedly referred to himself as "tough on crime."

That being said, as president, Trump has supported some criminal justice reform initiatives, NPR noted. For example, he supported and signed the First Step Act. He also famously pardoned Alice Marie Johnson, a woman who had been sentenced to life in prison for non-violent drug crimes, Business Insider reported.

Overall, taking a look at where the 2020 candidates stand on criminal justice reform hints at what types of policies they may pursue as president. As campaign season continues, you can expect these candidates to further flesh out their criminal justice reform platforms, so make sure to check their campaign websites to keep up-to-date with their latest initiatives.