States with more firearm laws tend to have the lowest rates of gun deaths, according to a study released Wednesday by Boston-based researchers, NBC News reports.

The researchers argue that their findings show that there is a role for more rigid gun-control legislation in America. By scoring individual states simply by the sheer volume of gun laws they have on the books, the researchers note that in states with the highest number of firearms measures, their rate of gun deaths is collectively 42 percent lower when compared to states with the fewest number of gun rules, NBC states. The study was published online in the JAMA Internal Medicine journal.

The study compares firearm fatalities in law-laden states such as Massachusetts (3.4 gun deaths per 100,000 individuals), New Jersey (4.9 per 100,000) and Connecticut (5.1 per 100,000). Gun-mortality rates in states with fewer firearms laws were higher: Louisiana (18.0 per 100,000), Alaska (17.5 per 100,000) and Arizona (13.6 per 100,000).

On Thursday, the Senate Judiciary Committee is expected to vote on a bill that would stiffen penalties for people who purchase guns illegally for others and to make gun trafficking a felony, NBC reports.

While the researchers acknowledge they cannot prove a definitive “cause-and-effect” link between tighter laws and a lower risk of gun-related homicide or suicide, but they did determine that in those states with the most firearm laws, there are the lowest rates of household firearm ownership, the article says.

However, the findings have been challenged by gun-rights advocates and a leading expert in public health and gun policy, which question the merits of the Boston findings and the rigor of the science behind the study.