The Alaska Supreme Court last week overturned the conviction of a 62-year-old Ketchikan man who had been found guilty in 2006 of failure to register as a sex offender.

In its April 25th opinion, the court writes that the original offense for which Byron Charles was convicted occurred in the 1980s, before the State of Alaska passed the Alaska Sex Offender Registration Act. That 1994 law required convicted sex offenders to register with the state, even if the offense took place before 1994.

In 2008, the Alaska Supreme Court ruled in Doe v. State that the sex offender registration act cannot be applied retroactively. Charles had previously appealed his conviction on the failure to register charge, but had not argued against the retroactive clause in state law. After the court’s 2008 decision, though, Charles added that argument to his appeal.

Lower courts ruled that Charles had essentially waived his right to use that argument by not bringing it up earlier. But in its April 25th decision, the Supreme Court decided otherwise.

The court writes that “permitting Charles to be convicted of violating a criminal statute that cannot constitutionally be applied to him would result in manifest injustice.”

With that in mind, the Alaska Supreme Court reversed Charles’ 2006 conviction of failure to register as a sex offender.