Maine's highest court has upheld a ruling that a 1999 sex offender law can not be applied retro-actively.

In its ruling, the Maine Supreme Court gave the legislature until March 31st to revise the law.

The case spurring the decision involved a Dixfield man who was convicted of raping a 13-year-old girl in 1996.

At the time, he was required to register as a sex offender every 15 years.

A law change in 1999 then required him to register every 90 days for the rest of his life. However, the court said Tuesday it was unconstitutional to apply those changes retro-actively.