Why doesn't the sex offender registry violate the US Constitutional ban on Ex Post Facto?

Answer 1

"Ex Post Facto" refers to punishing someone for an act that was legal at the time they committed the act.

For example:

There was a time when an 18 year old could legally possess and consume alcohol; however, as we know now, the government would end up raising the age to 21.

If the the age increased to 21 on March 1st, an 18 year old cannot be arrested for drinking in February. This is because, at the time he was drinking, it was legal for 18 year olds to drink - He was not breaking any laws at the time he was drinking.

However, in the instance you've mentioned, the Ex Post Facto defense does not apply. If the defendant is being placed on a sex offender registry, they committed an illegal sex offense. The act was illegal at the time the defendant committed it, thus the defendant can be legally punished.

Now, could there be a Constitutional question regarding offender registries? Absolutely, however, Ex Post Factois not the appropriate argument. One could certainly argue that being placed on to a public list after already serving a sentence is "Cruel and Unusual Punishment"; however, courts have looked at this issue before, and consistently put the safety of society over the rights of the offender.

Answer 2

The sex offender registry is considered regulatory, not punitive, and its primary purpose is public safety rather than punishment. Therefore, it does not violate the constitutional ban on ex post facto laws because it is not intended to punish individuals for crimes committed before the registry was established.