It’s not often that you’ll find the ACLU on the same side of an issue as President Donald Trump.

But in the waning days of the 115th Congress, lawmakers have the rare opportunity to show bipartisanship isn’t completely dead. For months, advocates and lawmakers have worked together to craft a criminal justice reform bill, known as the FIRST STEP Act, that enjoys broad support from the White House and members of Congress in both parties.

Only one thing stands in the way of this piece of genuine bipartisan reform: Mitch McConnell. The Senate majority leader has complete and absolute power to bring the FIRST STEP Act to the floor for a vote. Thus far, he has chosen to stand in the way of essential reforms that will help ensure incarcerated people who have served their time have a second chance at life.

So how did we get here?

On Nov. 15, an updated version of the FIRST STEP Act was introduced in the Senate after the original version of the bill passed the House by a wide margin in May of this year. The ACLU and other civil rights organizations opposed the House version of the bill because it failed to address harsh sentencing laws, which are the pivotal drivers of mass incarceration on the federal level.

Instead, the ACLU and other civil rights organizations continued to pressure the Senate to include federal sentencing reforms in its version of the legislation. Holding out seems to have led to improvements in the bill. The recent Senate version of the FIRST STEP Act, which we support, includes sentencing reform provisions that the ACLU and others have fought long and hard for.

The legislation, however, is not without its problems. It does not retroactively apply its sentencing reform provisions to people convicted of anything other than crack convictions, it raises serious concerns that it could lead to unconstitutional government spending on religious programming, and the bill precludes individuals from benefiting from some provisions due to citizenship and immigration status.

Nevertheless, the inclusion of concrete sentencing reforms in the Senate’s version of the FIRST STEP Act is an important improvement for advocates and directly impacted communities who have been fighting for sentencing reform for years. The provisions in this bill can directly improve the lives of people harmed by our broken criminal justice system.

Tell your senator to pass criminal justice reforms

The United States continues to lead the world in the number of people it incarcerates with 2.1 million people in prisons and jails, more than 180,000 of them in federal prisons on any given day. Black, brown, and poor people bear most of the burden of this country’s distinct dishonor of being the world’s top incarcerator. The Senate version of the FIRST STEP Act includes a few of the sentencing reforms necessary to begin to address mass incarceration and prison overcrowding on the federal level.

The new version of FIRST STEP would apply the Fair Sentencing Act of 2010, which reduced the disparity between the crack and powder cocaine sentences from a ratio of 100-to-1 to 18-to-1, retroactively to those sentenced before the law passed. This improvement would allow over 2,600 people the chance to be resentenced.

Retroactivity is a vital part of any meaningful sentencing reform. Not only does it ensure that the changes we make to our criminal justice system benefit the people most impacted by it, but it’s also one of the keys to reducing mass incarceration. The federal prison population has fallen by over 38,000 people since 2013 thanks in large part to retroactive application of sentencing guidelines approved by the U.S. Sentencing Commission.

The retroactivity of the Fair Sentencing Act is a hard-fought win for people in prison serving these sentences. Unfortunately, the FIRST STEP Act would not include retroactivity for the rest of its sentencing reforms, which minimizes its impact substantially.

The new, Senate version of the FIRST STEP Act contains several other important reforms to sentencing laws that have bloated our federal prison population and added to the racial disparities in the system. The new language expands the “drug safety-valve,” giving judges the discretion to reject mandatory minimums for people convicted of drug offenses while reducing the mandatory minimums for other drug offenses.

It also eliminates the practice of “stacking” gun sentences from the same incident on the top of the sentence for a drug crime or crime of violence. “Stacking” has resulted in countless people serving long, draconian sentences. These reforms are truly first steps to reducing mass incarceration, but they won’t apply retroactively, leaving thousands of people in prison

With the addition of these sentencing reforms, the Senate version is a modest, but important move toward meaningful criminal justice reform. But the system will not truly be reformed until every person receives a fair and just sentencing regardless of when they were sentenced. The FIRST STEP Act, if passed, truly represents the first step on the road to a more just criminal justice system.

Sen. McConnell needs to stop the obstruction and allow the Senate to vote on the bill.