Legal scholars long have struggled to determine the proper allocation of authority between judges and juries. But you don't have to be an expert to recognize that Allen Ryan Alleyne was treated unjustly by a federal court in Virginia.

The jury that convicted Alleyne for his role in the armed robbery of a convenience store specifically looked at the question of whether a gun was "brandished" by Alleyne's accomplice, a factor that would trigger a mandatory minimum sentence of seven years for any participant in the crime. The jury concluded that it wasn't (although it did agree that a gun had been "used or carried"). But when the judge sentenced Alleyne, he concluded that a gun had been brandished and sentenced him to the mandatory minimum.

Last week, Alleyne's lawyers asked the Supreme Court to set aside that sentence, but they acknowledged that to do so, the court must overturn its 2002 decision in Harris v. U.S., which allowed judges to determine whether a weapon was brandished.

As a general rule, the court should be cautious about overturning its own precedents. But the Harris decision, a 5-4 ruling, was logically at odds with a landmark ruling handed down two years earlier, Apprendi vs. New Jersey. Overturning Harris would do more than provide relief for Alleyne; it would also clarify that juries, not judges, are responsible for deciding whether a defendant committed a crime.

The Apprendi case concerned a man who fired shots into the home of an African-American neighbor. A judge had added two years to Charles Apprendi Jr.'s maximum sentence of 10 years after finding that the shooting was racially motivated. But the court ruled that the question of motivation should have been presented to a jury. Despite that holding, two years later in the Harris case the court said that a judge was free to determine on his own that a defendant had brandished a gun and should therefore receive extra punishment.

The Obama administration argues that the Harris case and the punishment imposed on Alleyne are consistent with the Apprendi ruling because they involve mandatory minimum sentences that fall within a sentencing range that would be available to a judge even without the brandishing finding. That's a distinction without a difference. Like Apprendi, Alleyne was sentenced to more time than he otherwise would have served because a judge decided unilaterally that he was guilty of a crime.

The Apprendi ruling didn't give juries total authority over what sentence a convicted defendant receives. Judges may adjust sentences based on a range factors, including a defendant's prior criminal record. In other words, they may decide whether a punishment fits the criminal as well as the crime. But whether a crime was committed is for the jury, not the judge, to determine.