TULSA, Oklahoma - Oklahoma has removed 2,400 sex offenders from its registry since a state Supreme Court decision six months ago.

The legislature passed a law in 2007 increasing the number of years sex offenders have to register and it was applied to people already convicted, but the Oklahoma Supreme Court said the law could only apply to people going forward.

When I was in the sex offender registration office, I met a man who was crying because he'd just learned he no longer has to register.

His crime at 17 was having sex with a girl he thought was also 17, but she was actually 14. For nearly two decades he's been registering as a sex offender.

The man, who we're calling Dave, will never have to register his address with Tulsa police again, after doing so every three months for the past 19 years.

Records show he's never failed to register and never been accused of another sex crime.

"I know people who deserve to be on this, but I never deserved to be on this," Dave said.

Dave pleaded guilty and served 14 months in prison. He's had to live with his mother, because most addresses are outlawed for sex offenders and he's struggled to get a good job and has never been able to take his kids to the park or attend their activities at school.

"They told me when I started it would only be for 10 years, then I got to the 7th year and I got another letter saying I had to do it for my lifetime," he said.

Because the Oklahoma law was applied to those already convicted, that led to a lawsuit that went all the way to the Oklahoma Supreme Court.

The court said it wasn't fair to change the registration of people convicted years before who were complying with the law, that it was like moving the finish line just as they approached it without giving them a hearing or a chance to tell their story.

So, the Department of Corrections is going through all 7,000 registered sex offender cases to determine who's already registered long enough and who should be taken off.

Dave said not all sex offenders are the same, although they get treated that way.

"They think every person on the sex offender list molested an infant and it's not true," he said.

Since the law passed in 2007, those considered level one sex offenders, a low risk to the community, must register for 15 years.

Level two offenders, a moderate risk to the community, must register for 25 years and level three offenders, people considered to be a serious risk, must register for life.