Good morning, Bulletin readers. As the debate over guns in schools continues, an investigation tallies the number of districts where teachers and staff can now be armed. Stanford researchers found that stricter gun regulations can protect young people. And a 17-year-old gun reform activist is eyeing elected office.

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WHAT TO KNOW TODAY

NEW from THE TRACE: Digging into the research on gun background checks. This week, House Democrats filed legislation that would extend background checks to nearly all gun sales. The policy is popular, with polls showing support reaching as high as 97 percent of American voters, including gun owners. But how much will it reduce crime? In a new explainer, Alex Yablon looks at a growing and complicated body of research into background checks and other gun-screening processes.

A group of Democratic senators introduced the Assault Weapons Ban of 2019.The bill would ban the sale of semiautomatic rifles and magazines that hold more than 10 rounds. Owners would be able to keep existing weapons. California’s Dianne Feinstein, who helped author the 1994 federal assault weapons ban, is among the bill’s sponsors.

Hundreds of school districts across the United States have armed school staff since Parkland. At least 215 districts have adopted such policies in the past 11 months, according to a Vice News investigation. The moves come despite the lack of evidence that allowing educators and staff to carry guns saves lives, and often over objections from local law enforcement and school insurance carriers. According to Vice, many districts have begun to arm staff without notifying state authorities, students, or parents — and are not bound by law to do so. Related: GQ goes inside a firearms training program for teachers.

Relaxed gun laws are linked to more adolescent deaths, a pediatric surgeon found. Stephanie Chao and her team at Stanford Medical School determined that states with relaxed gun laws had nearly twice as many adolescent firearm deaths as states with comparatively tight restrictions. Chao says she hopes to see more gun safety measures implemented. “Our study is not anti-gun,” she said. “Our study is pro-children.”

The Second Amendment does not apply to undocumented immigrants, a federal court ruled. The Ninth Circuit on Tuesday upheld a federal ban on gun ownership for people who enter the country illegally. A three-judge panel concluded that undocumented immigrants fall outside of “the core” of Second Amendment protections, due to the fact that they are acting unlawfully by living in the country without authorization.

A Kentucky Republican filed a bill that would allow guns in day care centers. The proposal introduced Tuesday would also let people with concealed-carry licenses bring weapons into elementary schools, bars, and some government meetings. The lawmaker has responded to past school shootings by arguing that guns are not part of the problem.

Lawmakers in Maine are pushing for a universal background check bill. The proposal would expand background checks to all private sales and transfers. But the state’s Democratic governor noted that voters rejected a similar ballot initiative in 2016. “The people have already spoken,” he said.

A teen gun reform activist is running for the City Council in Mesa, Arizona. Jacob Martinez, 17, became involved in March For Our Lives after the Parkland shooting. Now he’s running for elected office. “It’s my generation that’s going to be impacted by the decisions being made now,” he said.

The NYPD seized 9 handguns from four cops to prevent domestic violence. After two New York City police officers were revealed to be cheating on their partners, who are also police officers, the department seized weapons from all four cops because of “the potential for violent outcomes.” The weapons were taken under a section of the patrol guide that allows for the temporary removal of guns from officers in cases involving “stress as a result of family or other situations.”

A man was shot by his dog on a hunting trip in Mississippi. The hunter, a former Louisiana State University offensive lineman, was struck in the leg when the animal jumped onto a loaded gun that was sitting in his truck, causing the weapon to discharge. He was sent to the hospital where his leg was amputated. “The opportunities for an accident are there, and we just don’t realize it,” said one man who witnessed the shooting. “We think we’re being safe, but are we?”

ONE LAST THING

In the first week of 2019, hundreds of people lost their lives to gun violence. As of Tuesday evening, more than 300 people were fatally shot, according to Gun Violence Archive. Over 600 more were wounded. Those tallies include 10 young children and 49 teenagers shot, six mass shootings, and 44 unintentional shootings. The recent victims include an Alabama woman killed by her ex in a murder-suicide, a 17-year-old shot at a California elementary school, and four people wounded by gunfire at a party in New Mexico.