This sort of common-sense strategy has long been recommended by Mayors Against Illegal Guns, the group co-founded by Mayor Michael Bloomberg of New York. Yet in 2010, the latest date for which figures are available, just 44 of the nearly 80,000 Americans who flunked backgrounds checks because they lied or gave incorrect information were charged with a crime. That’s an indefensibly low number even given competing prosecutorial priorities (though consistent with the record of the Bush administration). But insufficient prosecutorial attention is hardly a reason to oppose new federal gun laws that would make Americans safer.

Nevertheless, the N.R.A.’s cynical effort to shift the debate to lax enforcement continues without letup. An N.R.A. official, Andrew Arulanandam, intoned recently that the government’s failure to aggressively investigate people who failed their background checks meant that people who should not be buying guns in the first place were escaping justice — in his words, “getting away scot-free.” He failed to mention that it is only because of the 1993 Brady Act, which the N.R.A. vehemently opposed, that the nation even has a system that can identify prohibited buyers and those who lie.

The hypocrisy of the N.R.A.’s argument that the problem is weak enforcement is exposed by its efforts over the years to undercut what enforcement there is. It has tried mightily to ensure that the Bureau of Alcohol, Tobacco, Firearms and Explosives lacks the leadership, resources and legal authority to do its job properly. Restrictions enacted at the gun lobby’s behest make it exceedingly hard to identify dealers who falsify sales records, for example, and bar the bureau from putting gun-sale records into a central database for speedy tracing of weapons used in crimes.

Further details of the N.R.A.’s anti-enforcement efforts were revealed by Dennis Henigan, a former vice president of the Brady Campaign, a leading gun-control group, in his 2009 book “Lethal Logic.” It recounts how the N.R.A. campaigned in the 1980s to weaken the 1968 Gun Control Act that President Lyndon Johnson pushed through after the assassinations of Martin Luther King Jr. and Robert Kennedy. The result was the Firearm Owners’ Protection Act of 1986, a misnamed law that has made it difficult to investigate and prosecute gun trafficking to this day. For example, it protects unscrupulous gun dealers by prohibiting A.T.F. agents from making more than one unannounced inspection a year. It also makes it hard to revoke their licenses. Those and other damaging provisions from the 1986 law should be tossed out as part of the new, still only hazily defined anti-trafficking measure Mr. Obama has pledged to fight for. The N.R.A.’s opposition won’t make that easy.