The measure, Congress' response to last year's Virginia Tech shootings, is the first significant federal legislation in years aimed at tightening gun laws. It seeks to expand the federal database used to screen gun buyers to include the estimated 2 million-plus people, including felons and mentally ill individuals, who are ineligible to buy firearms.
But the measure has created an unusual rift among gun-control groups.
Kristen Rand, legislative director of the Violence Policy Center, said there was "far more bad in this bill than good," expressing concern about a provision that could restore gun-owning privileges to some people now prohibited from purchasing firearms.
"It's certainly not this huge victory that the Brady Campaign is making it out to be," said Joshua Horwitz, executive director of the Coalition to Stop Gun Violence.
The bill represents a shift from the last major gun measure, which shielded gun makers and sellers from lawsuits arising from misuse of their weapons. It was passed in 2005 by a Republican-controlled Congress and signed by Bush. The year before, Congress allowed the 10-year-old ban on assault weapons to expire.
The legislation signed Tuesday, designed to improve the National Instant Criminal Background Check System, was the first gun measure to emerge since Democrats took over the House and the Senate a year ago. It was passed last month, in the waning hours of the 2007 legislative session.
Rep. Carolyn McCarthy, D-N.Y., one of the bill's sponsors, said it would "close the wide gaps in our nation's firearm background-check system to ensure violent criminals and the mentally ill no longer slip through the cracks and gain access to dangerous weapons."
Said White House spokesman Tony Fratto: "We saw with the terrible shootings at Virginia Tech last year that an incomplete system can have tragic consequences."
Even with the bill's enactment, the gun issue is unlikely to gain more prominence on Capitol Hill this year.
Democrats have shied away from the issue since the 2000 election, believing that their presidential candidate, Al Gore, lost support in rural states because he supported gun control.
The issue also doesn't fall strictly along party lines; eight Democratic senators recently joined 39 Republican senators in calling for repeal of a ban on carrying loaded firearms in national parks and wildlife refuges, saying the restriction "infringes on the rights of law-abiding gun owners."
Efforts to strengthen the background-check system have been debated for years, but the movement gained momentum after Seung-hui Cho killed 32 students and teachers at Virginia Tech before taking his own life April 16 in the deadliest campus shooting in U.S. history. He had been ordered by a court to undergo outpatient mental-health treatment and should have been barred from buying the two handguns he used in the rampage, but his name was never entered into the background-check system.
A White House-ordered review of the Virginia Tech shootings found that "accurate and complete information on individuals prohibited from possessing firearms is essential to keep guns out of the wrong hands."
Currently, 17 states provide no mental health records to the background-check system, according to the Justice Department.
The new law takes a carrot-and-stick approach to get states to report people ineligible to buy guns. It authorizes up to $250 million a year for five years to states to help pay the cost of providing the records and then threatens to withhold federal anti-crime funds if the states fail to act.
In addition to the support the bill received from the NRA and the Brady Campaign, it was sponsored by the unlikely pair of McCarthy, a leading gun-control advocate whose husband was killed and son wounded by a gunman on a Long Island train in 1993, and Rep. John Dingell, D-Mich., a staunch NRA ally who has helped thwart gun-control legislation in the past.
"While most would say we are an odd pair when it comes to this particular issue, I would suggest we are just two legislators trying to fix a legitimate problem," Dingell said.
But some gun-control groups aren't celebrating.
The Violence Policy Center and the Coalition to Stop Gun Violence contend that the Brady Campaign, eager for a victory, conceded too much to the gun lobby.
"This program is just a disaster in the making," Rand said, arguing that the new law could put guns back in the hands of dangerous people. She said the legislation allows veterans judged to be mentally incompetent to seek to get their gun privileges restored if they can show they are unlikely to endanger public safety or have received treatment and recovered.
Rand also said she was skeptical that Congress would follow through on providing the promised funding for states to enter the records of prohibited gun purchasers. "Frankly, we just don't trust that the NRA will lift a finger to see that the grant portion of the bill is fully funded," she said. Some states still might not provide mental health records because of their own privacy laws, she added.
Peter Hamm, a spokesman for the Brady Campaign, described groups like Rand's as "friends of ours," adding: "We're stunned and exasperated that they opposed this legislation."
The measure's benefits outweighed its risks, he said, noting that his group is concerned about the millions of mental health records that are not in the database.
The measure also divided gun-rights groups.