With nearly 2.3 million prisoners behind bars, the United States has the highest incarceration rate in the world. Rachel Barkow, who served on the U.S. Sentencing Commission from 2013 to 2019, examines how we got to this point and what can be done to help reform the country's justice system. She currently serves as the vice dean and professor of regulatory law and policy at the NYU School of Law.

In her recent book, "Prisoners of Politics: Breaking the Cycle of Mass Incarceration," Barkow argues that years of bad policies resulted in a vicious cycle. However, there is a path to undo some of the damage.

This interview has been slightly edited for clarity.

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CBS News: Your book argues that longer sentences contribute to more crime. How do you convince people that less incarceration means higher public safety?

Rachel Barkow: I do think that people have a sense that, "I'm going to lock them up and throw away the key." But, we never throw away the key. Ninety-five percent of the time, the person comes back out, and you are just kicking the can down the road. Incarceration is buying you some time, but the underlying issues the person might have, or the underlying cause of the crime in the first place, you're just putting off.

I like to think about it like your credit card bill. If you're in financial difficulty, and you can't pay your bills, you put them all on your credit card. You might think, "Phew, that problem is taken care of." However, the next month your credit card bill comes and there's interest. It gets worse and worse and the longer you don't pay, the worse things get. Long sentences are like that. While you're incarcerating people, not only are you not making them better, you're often putting them in environments where they are likely to become worse.

CBS News: We just passed the six month mark of President Trump signing the First Step Act into law. One aspect of the legislation helps alleviate certain mandatory minimum sentences, which are predetermined prison terms for certain crimes. What about arguments in favor of mandatory minimums, in that they create an equitable system of punishment?

Barkow: That was the thought, but I don't know why people assumed that would lessen disparities. Anyone who proposed that, forgot that prosecutors existed. A prosecutor does not have to charge you with the mandatory minimum. There is more than one drug crime in the federal code.

So, if I'm a prosecutor and I want to charge you with selling drugs, I have my pick of what I'm going to charge you with. That means, a prosecutor can pick and choose who gets charged with the full mandatory minimum and who doesn't. Instead of having a judge decide what a sentence should be, they've effectively allowed prosecutors to make that decision. That is really problematic. While the judge is at least an objective third party with no stake in the outcome, the prosecutor can threaten people with mandatory minimums to get them to plead guilty.

Mandatory minimums definitely made all the things it sought to solve worse. I fully recognize it was done with good intentions, but we are long past the point that anyone can claim to have a good intention for keeping it.

CBS News: The First Step Act also establishes what's known as "earned time credits" for the first time at the federal level. This system allows an inmate to earn time off their sentencing if they participate in programming while incarcerated. What stands out to you about this component?

Barkow: The last remaining question mark of the First Step Act is what will this earned time credit regime look like? Will there be enough programming? Will it be sufficiently funded? Are they going to do a good job making sure it's working well?

The people who need programming the most are high risk people. Every criminologist will tell you that. It's the best investment that we could make as a society, but the legislation makes them ineligible. It's only available for lower risk people. It's just a way for the lower risk population to cut their sentences, I think, in a politically palatable way. As a society we'd be much better off if we offered programming to high risk people.

So, an interesting wrinkle I think people might not know about, is Congress' decision to make whole groups ineligible for this, despite the fact that those are the very groups that need it the most. That was just pure politics, not based on evidence or what would be a good use of the resources.

CBS News: Why do you think there isn't more programming in place?

Barkow: There is a tendency in America to view everything as an individual decision: if a person comes out of prison and commits a crime, "That's on them." It's a little ridiculous though, because through interventions we can reduce the risk that it would happen.

We should want, during the time that they're in custody, to invest in all the things that can make criminal behavior less likely when they're released. There are things that we can do that would change the odds of that happening. The only reason that we don't, and the reason why we don't hold prisons accountable, is this weird sense people have that it's completely up to the individual. Maybe there's a cynicism that they will all fail anyways so why bother? But none of that is true.

It's good to remember there's a lot of things we can do that help people — and help us. You don't even have to be nice or empathetic, you could be truly selfish and say, "I'd like to be safer." I could be safer if instead of my tax dollars going to support facilities that do a terrible job when someone is incarcerated, they support facilities that offer the right kind of programming. That way, when someone gets out they're less likely to offend.

CBS News: If this was the first step, what's the next step for criminal justice reform?

Barkow: The First Step Act didn't really address currently incarcerated people who are serving excessively long sentences. It changed some mandatory minimums, but only from the day the act passed onward. For people currently serving the time, they did nothing. My idea would be that you have provisions to deal with currently incarcerated people who have long sentences. That's what I would do next.

We will not solve mass incarceration by relying on the federal government to do it. States need to take action. The federal government could create financial incentives, but we got where we are today from a lot of different political jurisdictions and actors making the same punitive decisions. To undo it, we're going to have to go back and have all those jurisdictions and individual actors make different decisions.

CBS News: Criminal justice reform is turning into a main issue for the 2020 election. We've already seen a few democratic contenders release plans or weigh in, including former Vice President Joe Biden, Senator Cory Booker and Senator Kamala Harris, to name a few recent high-profile unveilings. What do you look for in a candidate's platform on this issue?

Barkow: If it were me, the key things would be eliminating mandatory minimums and providing a mechanism for anyone who is currently serving a mandatory minimum. That way they could petition a court for relief. I think that's the most important thing that should be done at the federal level legislatively. It would be nice if we had legislation that just said, "The mandatory minimum idea was a failure. We thought it was going to eliminate disparities, instead it exacerbated them." Mandatory minimums don't help public safety, all they've done is create additional racial disparities and a lot of human misery.

If that can't be done, then I'd like to see a president who uses the clemency power to do the same thing. We have too many people serving sentences that are too long, and they have no mechanisms right now. The only place they can go is to the president of the United States.

For presidential candidates in particular, there are things they can claim they're going to do, but that would require Congress. So, all they're really saying is, "I as a president will ask for this." But if Congress says no, that's it. Then, there's the things the president can do on their own. They have a lot of authority, especially with clemency power.