The Supreme Court of the United States has ruled that a federal law requiring sex offenders to update their registration when crossing states lines doesn’t automatically apply to those who committed their crimes before the law was passed.

In a 7-2 ruling issued Monday in Reynolds v. United States, No. 10–6549, the court reversed the 3rd Circuit Court of Appeals that had dismissed a sex offender’s lawsuit challenging his arrest and conviction for violating the Sex Offender Registration and Notification Act, enacted in 2007.

Billy Joe Reynolds served four years in prison after being convicted of a sex offense in Missouri in 2001. After his release in 2005, he registered in Missouri but didn’t update his registration when moving to Pennsylvania in 2007. He was charged with knowingly failing to register according to the law and was sentenced to 18 months imprisonment. Reynolds sued on the grounds that his crime was before the U.S. attorney general issued an opinion in early 2007 that SORNA applied to pre-act offenders, but the 3rd Circuit ruled against him and dismissed the suit.

The SCOTUS overruled that appellate decision, sending the case back to the Circuit level for a decision on whether the AG had validly specified such an application. Justices Antonin Scalia and Ruth Bader Ginsburg dissented, writing that they believe the law applies to pre-act offenders regardless of what the AG has done.

Federal courts, including the 7th Circuit, have been split on this issue in recent years. The SCOTUS ruled in 2010 on an Indiana case, Carr v. United States, but the justices sidestepped addressing whether the SORNA registration requirements applied to the original sex offense and instead focused on when the interstate travel occured. In Carr, the court held that the SORNA doesn’t apply to sex offenders whose interstate travel occurred before the law went into effect.