Firearm deaths of children and teenagers rose significantly in states that enacted more permissive gun laws after the Supreme Court in 2010 limited local governments’ ability to restrict gun ownership, a new study has found.

In states that maintained stricter laws, firearm deaths were stable after the ruling, the researchers reported, and in some, they even declined.

Guns are the leading cause of death in the United States for people ages 1 through 17, according to the Centers for Disease Control and Prevention.

Dr. Jeremy Faust, an emergency room doctor at Massachusetts General Brigham Hospital in Boston, who was the study’s lead author, said he was dismayed to find that most of the children’s deaths were homicides and suicides.

“It’s surprising how few of these are accidents,” Faust said. “I always thought that a lot of pediatric mortality from guns is that somebody got into the wrong place, and I still think safe storage is important, but it’s mostly homicides and suicides.”

13 years of data

The study, published Monday in JAMA Pediatrics, examined the 13-year period after the June 2010 Supreme Court ruling that the Second Amendment, which protects an individual’s right to bear arms, applies to state and local gun-control laws. The decision effectively limited the ability of state and local governments to regulate firearms.The researchers classified states into three categories based on their gun laws: most permissive, permissive and strict. They used a Centers for Disease Control and Prevention database to analyze firearm mortality trends from 1999 to 2010 — before the Supreme Court ruling — and compared them with the 13-year period afterward.

Nationally, they found that the number of people younger than 18 who died from firearm injuries in the period after the ruling exceeded the projected figure for that time by about 7,400, with a total of about 23,000 fatalities.

But in the nine states with the strictest gun laws, youth firearm deaths did not increase. In four — California, Maryland, New York and Rhode Island — they dropped significantly.

The average age of those killed was 14, according to the study, which was co-authored by researchers from Yale New Haven Hospital, the University of California San Francisco School of Medicine and the schools of public health at University of Pittsburgh and Brown University.

Black children and teenagers had the highest firearm death rates before the 2010 ruling as well as the largest increases in death rates in permissive states after the ruling. In states with strict gun laws, however, the pediatric firearm mortality rates in the Black population did not increase after the ruling.

Mixed reaction

John Commerford, executive director of the NRA Institute for Legislative Action, called the study “political propaganda masquerading as scientific research.”

Advocates for stricter gun laws praised the study, saying it expanded the evidence that gun safety laws save lives.

“We have shown in the past that states that have the strongest laws when it comes to gun policy have a gun violence rate that’s 2.5 times less than the states with the weakest,” said Nick Suplina, senior vice president for law and policy at Everytown for Gun Safety. “Lawmakers that refuse to take action or further loosen laws are putting kids’ lives at risk.”

He also said that gun safety laws had multiple benefits: reducing accidental shootings while also preventing youth suicides and school shootings. “Three of four school shootings are committed with a weapon taken from the home of the family or a close relative,” Suplina said.

‘An epidemic that’s really getting worse’

Faust said he became interested in the subject when, curious about gun deaths in his own community, he looked up children’s gun fatality rates in Massachusetts and noticed that they were relatively low compared with national rates — and had not increased in at least 25 years.

“I wondered if that was an isolated thing, or is it something else?” he said, adding that it did not appear to be a random phenomenon.

The research team found that there was a flurry of legal activity in many states after the 2010 ruling, with some moving to tighten gun restrictions under the parameters of the ruling and many others loosening them.

Stricter steps taken by New York included expanding an assault weapons ban, implementing limits on magazine capacity, requiring background checks for ammunition purchases and passing a so-called red flag law that allows family members and law enforcement officers to petition courts to remove firearms from people deemed at risk. California passed a number of laws, including prohibiting the possession of magazines capable of holding more than 10 rounds.

“It was like a natural experiment,” Faust said, adding that he was shocked by the stark disparity in firearm deaths depending on whether a state tightened or relaxed its gun ownership laws. In states that took the more permissive approach, he said, “you’ve got an epidemic that’s really getting worse.”