The Fair Sentencing Act of 2010 brought a measure of sanity to the grossly unfair crack laws. Where once an offender faced a mandatory five-year sentence for carrying five grams of crack — the weight of two pennies — the new sentencing act imposes the same penalty only if the offender is convicted of peddling 28 grams. Just as important, the new law eliminates mandatory minimum sentences for simple possession, and it narrows the gap between the harsh crack sentences imposed most often on young, African American men and the far more lenient penalties for powder cocaine infractions more often associated with white and Hispanic offenders.

The Fair Sentencing Act, in other words, guarantees that those who break crack cocaine laws in the future will face a punishment tailored to the crime. But what of those who are serving long, unjustified sentences under the old and now discredited legal regime?

The U.S. Sentencing Commission has been tasked with developing sentencing guidelines for the new crack law and last week took up the issue of whether the reduced penalties may be applied retroactively. The Justice Department endorsed retroactivity but argued that crack offenders who had been convicted of a gun charge and those with longer criminal histories should not be allowed to seek lower sentences. While we appreciate the department’s legitimate public safety concerns, we do not believe this approach is warranted.

The most important reason to set aside the Justice Department’s approach is fairness. The old crack laws were draconian — and that is true whether they were applied to a first-time offender or to someone who also was found to be in possession of a weapon.

Concerns over public safety can be — and have been — addressed through other means. The most serious criminals and those deemed violent “career” offenders are not among the 13,000 or so inmates eligible for a potential sentence reduction. Moreover, no sentence could be reduced until a judge evaluates an inmate’s record and signs off on the reduction. The judge would have the authority to reduce only the penalties associated with the crack violations; penalties for other offenses, including gun infractions, would remain intact.

Federal judges have a good record in making such judgment calls. Judges rejected some 36 percent of requests for reduced sentences after the commission tweaked the crack guidelines in 2007 and permitted retroactive reductions. The commission recently documented that those who were released after their sentences were shortened recorded recidivism rates that were slightly lower than typical. Those with longer records or gun convictions were not automatically excluded from consideration, and they shouldn’t be this time around, either.