IT'S A CHILLING thought: Seung Hui Cho's rampage at Virginia Tech might have been avoided but for what might have seemed until recently a minor flaw in Virginia state policy.
In 2005 Mr. Cho's disturbed behavior persuaded a state special justice to declare him "an imminent danger to himself as a result of mental illness" after police detained him. Under federal law, that determination disqualified him from legally purchasing guns. Yet when he went to buy the semiautomatics he would use to shoot up his campus, he came up clean on the federal database. That's because Virginia authorities never reported Mr. Cho's status to the database, which relies on information that states decide to provide. A spokesman for Gov. Timothy M. Kaine (D) explains that the state's procedure for reporting dangerous individuals to federal computer systems is not triggered if they are released into outpatient care, as Mr. Cho was, but only if they are involuntarily committed. Now the governor is working on ways to require Virginia authorities to submit data on cases such as Mr. Cho's, too. It's the least the state can do.
Even with Virginia's fix, the federal database will be vastly incomplete. Only 22 states transmit mental health records to the system. Virginia, ironically, was among the more diligent, even if it still left a crack open for Mr. Cho to exploit. Among other things, state privacy laws and technical issues prevent others from reporting what Virginia routinely does.
Some in Congress are promoting a federal solution. One proposal is to provide an incentive for states to share information on felons, dangerously mentally ill patients and others disqualified from owning guns by helping states pay the cost of reporting the data. On the flip side, states might also face penalties for not submitting the information. Federal prodding might succeed where common sense has so far failed.
An impeccable federal background check database would make it more difficult for dangerous people to illegally obtain guns. That is an important step. Congress also can do more to stop the determined ex-convict or would-be mass murderer from bargaining for a cheap handgun on a street corner. Among other things, rejecting the so-called Tiahrt amendment and similar measures that restrict local police departments' access to federal gun-tracing information would help investigators across the country shut down the rogue gun sellers who account for a huge majority of the firearms used in crime.