Charleston, W.Va. ? Since 1968, federal law has prohibited the sale of guns to anyone adjudged mentally ill. But more than half the states cannot – or will not – supply the necessary mental health records to the FBI database that is used to conduct background checks on would-be gun buyers.

That could change following last week’s massacre at Virginia Tech. The U.S. House is considering a bill that would encourage states to share mental health records with the federal government by giving them more than $1 billion in grants to help cover the costs.

Privacy laws and lack of technical ability now prevent 28 states from sharing such information with the FBI’s National Instant Criminal Background Check System based in Clarksburg, W.Va., according to a Justice Department report.

“Every one of these records that is not transferred is the record of someone who federal law has said is too dangerous to buy a gun,” said Dennis Henigan, legal director of the Brady Center to Prevent Gun Violence.

In some cases, the proposed federal law would override state privacy laws that prevent police agencies from obtaining mental health records. In others, it would require costly changes to how mental health information is collected and stored.

A 2005 study by the Bureau of Justice Statistics found that about 18 states cite privacy laws as an obstacle to sharing complete mental health records, and 10 others cite inadequate communication between agencies, incomplete records or lack of resources.

West Virginia, for example, does not report involuntary psychiatric commitments to the FBI because the state doesn’t know how many such commitments there are.

Involuntary commitment in West Virginia is essentially a county procedure. And the counties don’t report the outcome of those procedures to the state.

“We don’t have a central state database,” said Jennifer Bundy, spokeswoman for the state Supreme Court of Appeals, which oversees the state’s court system. The court is working on a computer system that would gather that information, Bundy said, but it won’t be completed until 2010.

Other states face legal obstacles. In Pennsylvania, the state police can use mental health records for background checks, but a state privacy law prevents them from sharing the information with the FBI, said Jack Lewis, a spokesman for the Pennsylvania State Police.

In creating the background check system, Congress passed a law in 1993 that said states must supply mental health records on people who have been declared mentally defective by or have been involuntarily committed. But in 1997, the U.S. Supreme Court struck down that requirement, saying states cannot be forced to take part in a federal program of this sort.

“It’s a voluntary process,” said Jerome Pender, deputy assistant director of the FBI’s Criminal Justice Information Services Division, which includes the database. “There’s no requirement.”

The states that report at least some mental health records to the FBI are Kansas, Alabama, Arizona, Arkansas, California, Colorado, Florida, Iowa, Kentucky, Maryland, Michigan, Missouri, New Hampshire, New York, North Carolina, Ohio, South Carolina, Tennessee, Utah, Virginia, Washington and Wyoming, according to the FBI.

Between 1998 and 2005, more than 62 million background checks were conducted through the database. The latest federal figures estimate 980,000 gun permits were denied for various reasons at the local, state or federal level during that time. The system does not break down denials by category, but convicted felons, illegal immigrants and people with restraining orders against them are among those barred from buying guns.