A federal appeals court has overturned the 25-years-to-life prison sentence of a San Francisco man convicted of failing to register as a sex offender.

A judge sentenced James Calloway under California's three-strikes law following his 2001 conviction.

But the Ninth U.S. Circuit Court of Appeals in San Francisco ruled on Thursday that a jury should have had the opportunity to determine whether one of his previous convictions was serious enough to qualify under the three-strikes law.

The conviction in question dated back to 1993, when Calloway pleaded no contest to assault with force likely to produce great bodily injury. Assault is only considered a strike if the victim is seriously injured.

The San Francisco Chronicle reports that Calloway's sentence could be reduced to six years in prison if a jury rules the assault did not produce a serious injury.