GOV. MARTIN O’MALLEY’S campaign to enact one of America’s toughest firearms laws faces its final test in Annapolis as it heads toward a vote in the House of Delegates. As in the state Senate, where the measure was approved last month, some lawmakers in the House are skeptical of the legislation’s central feature: requiring that handgun buyers submit to a tough licensing regime, including fingerprinting by state police.

The skeptics would do well to read testimony about a recent case study, conducted by a Johns Hopkins University researcher, that examined what happened after Missouri, which had a similar firearms permit system for 25 years, repealed it in 2007.

The main effect: Almost immediately after the law’s repeal, there was a sharp drop in the average elapsed time between the purchase of guns and their use in the commission of crimes in the state. The study’s author, Daniel W. Webster, director of the Center for Gun Policy and Research at Johns Hopkins University’s Bloomberg School of Public Health, said this indicated that straw purchasers had been emboldened by a weaker state law.

Using figures furnished by Missouri law enforcement agencies and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives, Mr. Webster found that by 2011, about 71 percent of guns recovered from crimes in Missouri had been purchased in-state; before the law’s repeal four years earlier, that share was 56 percent. Similarly, by 2011 more than a third of the guns used in Missouri crimes had been purchased in-state in the preceding two years; before the 2007 repeal, the comparable figure was just 15 percent.

Mr. Webster also found that, even as the murder rate declined nationally and, to a lesser degree, in the Midwest, it spiked by about 25 percent in Missouri in the four years or so after its gun permit system was repealed.

The study results are striking but not really surprising. They simply illustrate that criminals and their friends and associates are reasonably rational, in the sense that they do not want to submit fingerprints to obtain a permit for the purchase of firearms. In other words, a tough permitting system acts as a disincentive to criminals seeking guns.

That’s the logic behind the legislation backed by Mr. O’Malley (D). As things stand, Maryland, like Missouri and other states, is vulnerable to “straw purchasers” and buyers who would use fake IDs to procure weapons. But states such as Massachusetts, New York, New Jersey and Iowa, which require that buyers both apply directly to a law enforcement agency for a firearms permit and submit to fingerprinting, deter such ­purchases.

Tougher gun laws in a small state like Maryland will not end violent crime or stop criminals from procuring guns. More likely, it will drive criminals and their surrogates to seek weapons in states with weaker laws, such as neighboring Virginia. (In the process it may also drive up prices.)

But just as Missouri provides a stellar example of the perils of lax legislation, any state that enhances deterrents to criminal gun buyers sets a national example and helps provide national momentum toward sounder laws. Maryland delegates should consider that rationale as they weigh Mr. O’Malley’s legislation.