DENVER — Supporters of universal background checks for gun purchases in Colorado say 104 denials in the first six months of the law show that the regulation is working.
But the number alone doesn't present a clear picture of the law's effect.
Private-seller transaction data don't separate checks conducted at gun shows — which have long been required — from newly mandated checks on private and online sales.
Opponents say the way the numbers are tracked calls into question the accuracy of the figures that gun-control supporters and Democratic lawmakers have used in touting the law's success.
"It significantly changes, in my opinion, the validity of the Democratic talking points," said Republican Sen. Greg Brophy on Thursday.
"I question whether really any background checks are being run on private treaty sales outside of gun shows," he added.
Democratic Senate President Morgan Carroll, who sponsored the universal background check bill, acknowledged it would be good to have more complete data. She said, however, that the numbers indeed show "that background checks in general work."
Overall, there have been more than 6,000 private background checks since the new law went into effect, according to the Colorado Bureau of Investigation, which conducts the reviews. Bureau spokeswoman Susan Medina said the agency isn't required to keep track of how many of those were at gun shows.
Private-seller transactions represent a new category of gun sale tracking data. Before the expansion, all background checks were tracked in one category.
From January 2013 to June 2013 there were 4,243 total denials. It's not clear how many of these were from gun show sales, and checks on private and online sales weren't required at that time.
From July 2013 to December 2013, there were 3,108 total denials, a figure that includes the 104 rejections from gun shows, private and online sales.
When Democrats this week rejected a Republican proposal to repeal the universal background check law, they repeatedly mentioned the 104 denials and the more than 6,000 private background checks and said the numbers proved the law they passed last year is working.
Carroll acknowledged Thursday that it would be better to have more data, "if you want to be accurate about tying things for the law."
"We've relied on the public data that's been available, and we'll continue to look at any data we get," she said, adding, if authorities have "the ability to make a more refined way of how they track that, it can only help."
The bill was among a package of gun laws that ruling Democrats in the Colorado Legislature passed in response to mass shootings at a suburban Denver movie theater and Connecticut's Sandy Hook Elementary School.
Among the 104 denials — a number that can go down pending appeals — one had a homicide on their record, six had restraining orders, and 16 had assaults.
Republicans have express frustration about the way denials have been tracked.
"Why would you not keep track of that?" asked Republican Sen. Steve King. "It seems to me that if you're going to make evidence-based decision making, you need good evidence, you need good statistics."