Before President Bush left Washington for the Mideast, he signed into law the first major federal gun control measure in more than 13 years.
If the new law had been in effect last April, it might have prevented the Virginia Tech shooter, Seung-Hui Cho, from buying a weapon at a gun store.
"The Virginia Tech killer should have been stopped at the gun store," Paul Helmke of the Brady Center to Prevent Gun Violence said. "He was a prohibited purchaser. He had been found a danger to himself and others because of mental illness. Virginia did not send that information in."
Even before the Virginia Tech tragedy, in which Cho killed 32 people before shooting himself, federal law required states to put the names of people declared mentally ill by a court into an FBI database. The trouble was too many states simply did not do it. Some claimed they did not have the money and resources.
The new law authorizes up to $1.3 billion in federal grants so states can improve their tracking of people who shouldn't be allowed to buy a gun. But it took years for support to build, even though the measure had the backing of the National Rifle Association.
"We've tried to get this done in federal legislation since the mid-90s. But it was opposed by the mental health lobbies. They felt it was unfair to stigmatize that person and put him into the federal system," NRA spokesman Wayne Lapierre told ABC News.
Veterans groups also worried that military personnel could be singled out if they had been treated for combat-related stress.
Then came Virginia Tech. Nationwide shock and revulsion overcame all opposition. Relatives of the victims campaigned hard for passage and Congress passed the measure unanimously.
Peter Read, whose daughter Mary was killed at Virginia Tech, was thrilled when the bill passed and Bush signed itinto law.
"Basically our reaction was 'thank God,' because this is something we've been praying for," he said.
Still, there is a loophole in the new law. While it does cover all sales at licensed gun stores, it does not apply to all sales at gun shows, where unlicensed vendors are not required to run background checks.
Many gun owners are outraged at the thought of the government interfering with private sales at shows, but some members of Congress have said they will try to pass additional legislation this year aimed at making it harder for the mentally ill to buy guns anywhere.