Monday's 6-3 decision, written by Justice Samuel Alito, deals with provisions of the Armed Career Criminal Act. The law makes defendants eligible for longer prison terms if they have three prior criminal convictions for crimes that are either violent felonies or serious drug offenses.

A jury convicted Gino Gonzaga Rodriquez of possessing a gun as a convicted felon. Prosecutors said his five prior convictions — two for burglary in California and three for drug trafficking in Washington — should have led to a 15-year prison sentence.

But a federal judge imposed a sentence of 92 months and the 9th U.S. Circuit Court of Appeals in San Francisco agreed.

At issue was what makes a crime a serious drug offense. Judges sometimes look at the length of the sentence prescribed by state law.

In this case, the question was whether the additional time that state law imposed because someone is a repeat offender can be used to trigger the still harsher penalties under the federal sentencing law. The Supreme Court concluded it can.

Justice David Souter, joined by Justices Ruth Bader Ginsburg and John Paul Stevens, dissented. Souter said the court's ruling would make life more complicated for trial courts trying to calculate prison sentences.