We've already discussed Martin O'Malley's position on marijuana, but his opinion on how to treat veterans who have been discharged for anything related to the fact they were homosexual touches on something very interesting. Governor O'Malley wants automatic expungement – clear records – for those soldiers. Similarly, in the private sector, there are a number of people who were convicted for something that is now either legal or decriminalized.
Before Lawrence v. Texas, 539 US 558 (2003), states had anti-sodomy laws, which were often used to arrest homosexual men and women, resulting in a consensual, adult relationship leading to a spot on the sexual offenders registry. Romeo and Juliet laws, like Texas Penal Code, Section 22.011(e) have started to be passed in various states because teenage lovers ended up on the list. Streaking across the field can result in the same thing, the prospect of which drove a high school student to suicide, so states like Colorado, through C.R.S. 18-7-302 (2015) (PDF warning) have reclassified indecent exposure laws to reduce a first-time conviction to a misdemeanor rather than a felony.
For people who are currently registered – but shouldn't be – there are ways to get yourself off the list and back to living a normal life. It usually involves filing a petition with your state's Department of Justice, providing them with a copy of your criminal record, and providing them with a copy of the amended law, showing that you are currently being forced to register despite the statute under which you were charged has been amended or repealed.