DENVER (CN) - A gun control expert and proponent of background checks had a tough time defending his case in Colorado's gun control trial.
Monday was day six in the federal trial brought by 31 Colorado pro-gun groups and people who claim that three bills regulating gun use in Colorado are unconstitutional.
The defense called Daniel Webster of the John Hopkins Center for Gun Control to the stand Monday. Webster is famous for his study on how the repeal of gun control laws in Missouri in 2007 affected homicides and the crime rate. The study has been cited by media outlets such as PBS and the BBC to show why gun control might work.
In response to questions from defense attorney Matthew Grove, Webster said data showed a 23 percent increase in homicide rates after the repeal of gun purchase limits in Missouri.
He was asked about similarities and differences between Missouri's previous background check requirements and Colorado's.
"Colorado might be more effective in that it covers all firearm transactions," Webster said.
Webster seemed challenged by some questions from plaintiffs' attorney, David Kopel. Kopel asked Webster why he studied only the sale of handguns and did not address the issue of loaning firearms.
Webster said he examined the policy of transfer but then answered, "I don't remember."
Kopel then asked if he got his information on trace data from the Alcohol, Tobacco and Firearms Bureau. Webster said he did.
Kopel asked if Webster knew there was a disclaimer on the ATF's website about the reliability of the trace data. Webster did not give a clear answer on whether he did or not.
Kopel pointed out that the Congressional Research Center said trace cannot be used to describe the path of a gun and how it would get to an individual or a criminal.
"I don't know what the Congressional Research Center said," Webster responded. "I don't think it is relevant."
Finally, Kopel asked why Webster showed only what happened to the homicide rate after the repeal of the gun ban in 2007 and not for other years. Kopel showed data indicating that in 2009 the homicide rate in Missouri declined.
Webster said the reason the declining homicide rate may have been because "there are a variety of changes in social conditions."
After Kopel's cross examination, Grove asked whether the errors Kopel pointed out would change Webster's findings. Webster responded with a short "no."
The defense is expected to close Wednesday or Thursday. The plaintiffs closed in the first week of the trial.
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