Study: 2 gun-control laws really do lower homicides (3 others don't)

Firearm laws that strengthen background checks and require permits to purchase a gun are effective in reducing gun homicide rates, according to a study published by the Journal of the American Medicine Association Internal Medicine.

The study by doctors and scientists from Harvard Medical School, Boston Children's Hospital and Texas Children's Hospital in Houston was released Monday.

Researchers evaluated peer-reviewed articles from 1970 to 2016 to assess the effect of gun laws on firearm homicides. The laws were divided into five categories:

Curbing gun trafficking

Strengthening background checks

Improving child safety

Banning military-style assault weapons

Restricting firearms in public places and leniency in carrying guns

The scientists found that overall, stronger guns laws did lower homicide rates. But what seemed to make the difference were robust background checks and permit-to-purchase requirements.

Laws designed ban assault weapons, improve child safety and interdict gun trafficking did not have any effect on homicide rates.

As for restrictions on concealed carry and carrying guns in public, the jury is still out. The evidence was mixed, according to the study.