With Congress set to debate the emerging plan to expand background checks, conservatives and Republicans — and even a few red state Democrats — continue to traffic heavily in deliberate misdirection and distortions about the proposal. They are getting widespread media play and are dominating the debate.
So I asked Daniel Webster, a leading expert on gun violence who is the director of the Johns Hopkins Center for Gun Policy and Research, to respond to many of their arguments. Footnotes are at the end.
Criminals won’t obey any background check laws. So why would expanding the current law do any good?
The logic of this argument is flawed. It could be used to dismiss the utility of virtually any law because criminals will disobey it. The illogical exemption of private gun sales from background checks is the very reason that criminals don’t currently have to obey existing background check laws.
State laws prohibiting high-risk groups — perpetrators of domestic violence, violent misdemeanants and the severely mentally ill — from possessing firearms have been shown to reduce violence. [1, 2] One of my studies found that a number of state laws prohibiting individuals under a domestic violence restraining order from owning guns produced an overall 19 percent reduction in intimate partner homicides. 
Meanwhile, my research has shown that state universal background checks — along with other state laws designed to increase gun seller and purchaser accountability — significantly reduce the number of guns diverted to the illegal market, where the above high risk groups often get their guns [4, 5].
At the same time, the success of these state gun laws in reducing the diversion of guns to criminals is undermined by gaps in federal laws which facilitate interstate gun trafficking from states with the weakest gun laws to those with the strongest gun laws. [6, 7] For example, we found that states without universal background check laws had 30 percent higher levels of exporting across state lines guns that were later recovered from criminals. 
Is there any proof that guns used in violent crimes fell into the hands of the people who committed those crimes because of the private seller loophole?
Yes. My research has shown that failure to require background checks for firearms sales by private gun owners is associated with significantly higher levels of guns diverted to criminals both in-state and out of state. See the research cited above on state universal background check laws, diversion to the illegal market, and trafficking.
Isn’t it already illegal for a gun trafficker to buy guns at a gun show and then sell them out of the trunk of his car in, say, Chicago or New York or many other major cities? If so, why do we need to expand background checks?
It is illegal for a gun trafficker to purchase guns from a private seller in a state that does not regulate such sales and sell them in another state. However, because private gun sellers have no obligation to assure that purchasers have passed a background check or to maintain records of the sale of their firearms, it would be incredibly hard to prosecute that trafficker for a gun later used in a crime, because there’s no evidence he transferred the gun to the criminal.
So the trafficker can break existing law with something close to impunity. Expanding background checks would force the trafficker to prove he’d performed the check or be prosecuted — a much stronger disincentive to lawbreaking.
Even if we do close the loophole, won’t criminals simply get guns in another way?
Quite often not. Certainly some will find ways to get guns even with background checks. But the studies cited above show that state universal background checks, and state laws that prohibit criminals and other high risk groups from purchasing guns, reduce gun availability of guns to high risk groups.
This question also implies that criminals can always find a gun, no matter what we do, which is also inconsistent with the facts. Although a gun is an excellent tool to use if you are a robber for increasing compliance of victims, only 29 percent of robberies reported in the National Crime Victimization Survey involved the robber’s use of a firearm.  Data from in an in-depth study of the underground gun market in Chicago found that only twenty percent of male arrestees who participated in an anonymous survey reported that they had owned a handgun. Sixty percent of those who did own one reported that it had taken them more than a week to search for and obtain a handgun. Criminals were wary of purchasing firearms from sellers they did not know or trust, often reported difficulty finding a trusted supplier of guns, and faced considerable mark-ups in price from the legal market. 
Is there any proof that closing the private seller loophole would reduce gun violence?
Missouri’s repeal of its permit-to-purchase licensing and private handgun sale background checks law in August 2007 provides an example. Immediately following the repeal of this law, the share of guns recovered by Missouri police agencies that had an unusually short time interval between retail sale and crime — which is indicative of trafficking — more than doubled. The share of crime guns that had originally been sold by Missouri gun dealers rose sharply. 
There is also evidence that repeal of this law increased gun violence. Data from the U.S. Centers for Disease Control and Prevention show that when the mean from first three years of data following the repeal of the law are compared with the mean from the prior nine years, the rate of homicides with guns increased 25 percent in Missouri while nationally there was a 10 percent decline.
People determined to sell guns to prohibited parties for a profit often get their guns from a federally licensed gun dealer, in which case those people pass background checks. So how would closing the private seller loophole change anything?
If the loophole were closed, when gun is traced after confiscation from a prohibited person back to a private seller, police investigating the case could interview the private seller, who would then have to provide records indicating that he had transferred the gun legally with a background check. The need to do this would be another disincentive to lawbreaking.
Isn’t it already illegal for someone to buy a gun over the internet without undergoing a background check?
Not if the buyer and seller live in a state that does not require background checks for firearms sold by private partners.
1. Wintemute G.J., “Broadening denial criteria for the purchase and possession of firearms: Need, feasibility, and effectiveness.” Pages 77-94 in Reducing Gun Violence in America: Informing Policy with Evidence and Analysis, Daniel W. Webster and Jon S. Vernick, Eds., Baltimore, M.D.: Johns Hopkins University Press, 2013. [link] (Chapters from Reducing Gun Violence in America reprinted by permission of the publisher.)
2. Zeoli A.M., Frattaroli S. “Evidence for optimism: policies to limit batters’ access to firearms. Pages 53-64, ibid.
3. Swanson J.W., Robertson A.G., Frisman L.K., Norko M.A., Lin H.J., Swartz M.S., Cook P.J. “Preventing gun violence involving people with severe mental illness.” Pages 33-52, ibid.
4. Webster D.W., Vernick J.S., Bulzacchelli M.T., Effects of state-level firearm seller accountability policies on firearms trafficking. Journal of Urban Health 2009; 86: 525-537. [link]
5. Webster D.W., Vernick J.S., McGinty E.E., Alcorn T. “Preventing the diversion of guns to criminals through effective firearm sales laws.” Pages 109-122 in Reducing Gun Violence in America: Informing Policy with Evidence and Analysis. [link]
6. Braga A.A., Gagliardi, P.L. “Enforcing federal firearms laws against firearms traffickers: Raising operational effectiveness by lowering enforcement obstacles.” Pages 143-156, ibid.
7. Braga A.A., Cook PJ, Kennedy D.M., Moore M.H. “The Illegal Supply of Firearms.” In Crime and Justice: A Review of Research Volume 29, Chicago: University of Chicago Press, 2002. [link]
8. Truman J.L. Criminal Victimization, 2010. National Crime Victimization Survey. NCJ 235508. Washington, DC: United States Department of Justice, Bureau of Justice Statistics; September 2011. [link]
9. Cook P.J., Ludwig J., Venketesh S., Braga A.A. Underground gun markets. The Economic Journal 2007;117;F588-F618. [link]