It makes one wonder how accurate the email part of a federal sex-offender database, required by a new federal law, can be. As they are now, "sex offender registries are often inaccurate and incomplete," the Idaho Statesman reports, citing a recent study by the US Justice Department. "The national sex registry is missing information on 22% of state-level sex offenders, the federal investigators found. Driver's license information, Social Security numbers and basic addresses are regularly absent," the DOJ's Office found. The FBI maintains the national sex offender registry. "As sex registry information becomes more widely accessible via the Internet, investigators sound alarms about the databases used to monitor the nation's 644,000 registered sex offenders," according to the Statesman. "The concerns coincide with more fundamental questions about whether the stigmatizing registries go too far." The new federal law requiring that sex offenders provide their email addresses in addition to other contact data was signed last October (see this Wired blog).