President Trump just backed the prison and criminal justice reform bill, the First Step Act. Not only is Trump's endorsement an exceptional display of bipartisanship in a time of partisan rancor and stagnation, but it's also a groundbreaking moment for the modern American presidency. Presidents from both parties since the 1980s, from Bill Clinton to Ronald Reagan, contributed to a quadrupling of the American prison population despite violent crime plateauing. For Trump to sign into law what former President Barack Obama never could, free 4,000 people with a single stroke of a pen, and set hundreds of thousands of other prisoners on a course to rehabilitate their lives and potentially leave prison would be nothing short of a miracle.

The First Step Act primarily enacts back-end prison reform, changing how the prison system treats people who are already incarcerated with a view to reducing recidivism. It would create opt-in rehabilitative and vocational programs, which for low-risk prisoners can apply as credits to reduce prison sentences. It also makes a number of long overdue reforms, such as banning the handcuffing of pregnant prisoners (yes, that happens).

The bill's name acknowledges its legislative limitations; it's exactly what it says it is, a first step. Even so, the First Step could reduce sentences for low-risk offenders by as much as 40 percent. That's a pretty big leap forward from the current system, which tends to take low-risk offenders, derail their lives and make them permanently unable to make a living outside of crime.

Not only is this good moral policy, but it's a fiscally conservative policy as well. The United States currently spends $80 billion per year on our prison system. The CBO found that while the assumed welfare requirements of released prisoners would add $214 million and reduce revenue by $4 million in the next ten years, the lowered costs of prisons would reduce discretionary costs by $342 million. In ten years, the First Step Act would save the federal government $100 million, arguably a drop in the bucket in the short term, but savings that don't even include the long term economic benefit of increased two parent households and prisoners gaining the tools to help them more quickly re-enter the work force and stay off welfare.

It's also smart politics. By signing the First Step Act into law, President Trump can set off on a new foot, undoing some of the damage from those racially tinged gaffes and inconsiderate tweets ahead of the 2020 election. With Jeff Sessions out as attorney general and Trump himself professing his openness to legalizing marijuana, Trump could become the single greatest president for criminal justice reform in modern American history.

Consider: If Trump not only helped prisoners secure earlier releases, more humane living conditions, and lower their risk of recidivism with the First Step Act, reducing the number of nonviolent drug offenders entering prison, and retroactively pardoned nonviolent drug offenders like Alice Marie Johnson, he would do more for criminal and racial justice than any president in half a century.

We are supposed to be a nation of law and order, but our current prison system certainly doesn't encourage that. If a single mistake dooms a prisoner to a lifetime of recidivism due to lack of rehabilitation and an unnavigable mess of possible parole violations, then we're effectively crafting a permanent underclass of people who cannot escape a life of crime.

The First Step Act charts a new course, separating murderers and rapists who belong in prison for the long haul from those Americans worthy of the opportunity to rehabilitate themselves and rejoin civil society.