“This woman doesn’t belong in prison for 10 years for what I understand she did. That’s just crazy.” So said federal district Judge Richard A. Gadbois Jr. before sentencing Tonya Drake to a mandatory minimum of 10 years behind bars.

Tonya, a financially desperate single mother, mailed a package that, unbeknownst to her, contained 232 grams of crack cocaine. While Judge Gadbois thought the sentence unnecessarily harsh, federal law left him no choice: “There’s nothing I can do about it.”

Today, an unlikely coalition of conservatives and liberals is seeking to scale back federal mandatory minimums. Senators Dick Durbin (D–IL) and Mike Lee (R–UT) have introduced the Smarter Sentencing Act, which would revise federal mandatory minimum sentences for nonviolent drug offenses. The Smarter Sentencing Act is narrowly tailored to address one of the most pressing problems with mandatory minimums —arbitrary, severe punishments for nonviolent offenses—while leaving for another day the question of whether mandatory minimums should apply to violent crimes.

How did we get here in the first place? For most of the 19th and 20th centuries, federal trial judges had broad, virtually unlimited sentencing discretion. Congress revised that system in the 1980s. The Sentencing Reform Act of 1984 established the United States Sentencing Commission and directed it to promulgate Sentencing Guidelines that would regulate and channel a sentencing court’s discretion. In some instances, Congress decided to eliminate the courts’ discretion by requiring courts to impose a mandatory minimum sentence for certain types of crimes.

Mandatory minimums were intended to address widely acknowledged problems with the criminal justice system. But good intentions don’t necessarily give rise to good results. In particular, some drug offenses, which make up a significant proportion of mandatory minimums, can give rise to unduly severe punishments. The difference between a drug quantity that triggers a mandatory minimum and one that does not will often produce a “cliff effect.” For example, someone with 0.9 grams of LSD might not spend much time incarcerated, but another fraction of a gram will result in a five years behind bars. It is difficult to conclude that the additional one-tenth of a gram demands a minimum sentence of five years’ imprisonment in every case, regardless of its facts.

The Smarter Sentencing Act would allow judges to sentence nonviolent drug offenders below a mandatory minimum if the court finds that the defendant is not a serious offender (that is, the defendant has a limited or no criminal history, as defined by the U.S. Sentencing Guidelines, and no prior firearm, racketeering, terrorism, or sex offense convictions). The act would also make retroactive the Fairness in Sentencing Act of 2010, which prospectively reduced the disparity between the amount of crack cocaine and powder cocaine needed to trigger mandatory minimum sentences.

Mandatory minimum sentences have wrought terrible injustices in certain cases. Granting district courts some additional limited sentencing discretion would improve the status quo without returning us to the era of unbounded judicial discretion.

It’s encouraging that, at a time when bipartisan consensus is difficult to come by, there is broad agreement that there are some problems with our federal criminal laws that ought to be addressed. Too many mandatory minimums for nonviolent drug offenses committed by low-level offenders do not serve the ends of justice and leave no room for mercy.