For further evidence that state certification systems don't function well even for the easy stuff, look to the latest from Michigan. A state audit there recently found that 222 licensed school personnel had criminal records, the vast majority of which were unknown to both the state and the school districts where they were employed. Education officials blame this oversight on a lack of regular communication with state prosecutors and have announced grand plans to check in twice a year with the Michigan police to get updates on any of the more nefarious activities committed by teachers.

While keeping tabs on crimes committed by teachers is certainly a sensible idea, the bigger problem is that states are all still employing a hopelessly antiquated way of doing background checks on their prospective teachers: they only check on crimes committed in that state. This may have been a sound approach in the horse-and-buggy era, but in today's mobile society it constitutes the taking of an unconscionable risk. The state officials who stamp teachers' licenses may be able to rest easy with such a system, but students and their families certainly cannot.

On a related note, a principal at the Community Initiatives Academy, a private school in Baltimore, knowingly hired a convicted murderer as a teacher, but left students and families in the dark about her decision. The teacher allegedly proceeded to sexually abuse three students. Principal Christina V. Philips Holtsclaw defended her decision to hire the man to the Baltimore Sun: "This was second-degree murder... It wasn't something where he was a murderer out there killing people. As a black man, I gave him a second chance. I'm not glad for what happened. I'm sorry. But at the same time, I don't think my judgment was wrong at the time." While Maryland does require private schools to conduct background checks, they're not prohibited from hiring people who have been convicted of violent crimes - a loophole that we're betting gets closed real soon.