Do Sex Offender Registries Reduce Sex Offenses?

Today, in Anderson v. Holder,  the U.S. Court of Appeals for the D.C. Circuit rejected a constitutional challenge to the District of Columbia’s sex offender registry.  Specifically, the court rejected a claim that the law enacting the registry violated the Constitution’s Ex Post Facto clause because it required individuals to register who had committed covered offenses prior to enactment of the law.  Concluding the registry is “civil and nonpunitive” in intention and effect, the court determined its application to prior offenses did not constitute retroactive punishment.

Properly designed sex offender registries may be considered civil and non-punitive regulatory schemes as a matter of law, but is that how they operate?  Coincidentally, Alex Tabarrok had a post on Marginal Revolution yesterday surveying some of the evidence, and it’s not encouraging.  One study found such registries have a mild deterrent effect but can encourage recidivism.  Another, which looked specifically at D.C., found little evidence registries serve their intended purpose of preventing additional sex offenses or discouraging recidivism.

UPDATE: Just to clarify, the first study found that requiring sex offenders to register has a mild deterrent effect, but that making such information public (as provided for under some registry laws) may deter nonregistered offenders but can encourage recidivism by registered offenders.