This is where ex past facto decisions come into play. If a jurisdiction has declared their registry as punitive, then nobody currently on it can be held to a new stricter law. Also, if they change the law to be more lax, they cannot revert back and have it apply to any registrant that was on the lax laws. This is probably one of the deciding factors in Ohio right now. If they pass the lax laws and being in the 6th circuit, they can never go back.