In a fractured decision last week, the U.S. Supreme Court upended federal sentencing guidelines that had been enacted 20 years ago. The court’s ruling rightly restores to judges greater discretion in determining the length of prison terms without completely scrapping the guidelines devised by Congress in 1984.

With a different 5-4 majority of justices supporting each of the two parts of the ruling, the court found that judges have been improperly adding time to some sentences by considering facts not proven to a jury. In the second part, the justices said the guidelines, which are unconstitutional if mandatory, can be used voluntarily by judges as part of their decision making.

The aim of mandatory sentences was noble. Congress hoped to force consistency around the country and to guarantee that a person convicted of a federal crime in Maine would receive the same treatment as a person in Virginia, Texas or California. But the guidelines fell victim to overzealous politicians eager to prove that they were tough on crime. Sentence lengths increased as a result, and some relatively minor crimes were punished with draconian prison terms.

There’s no guarantee that sentences will get shorter, and prosecutors can appeal any they feel are too lenient. The ruling restores the authority of federal judges to sentence criminals based on the specific circumstances of a case.

Congress is predictably upset with the court’s decision. Before rushing in with a legislative fix, however, Congress should wait and see what the effects of this ruling are. Everyone seems to be after the same end: Fairer sentences.