How gun laws have changed in the 5 years since Sandy Hook

— -- Shannon Watts, a mother of five who became a gun control activist in the wake of the shooting at Sandy Hook Elementary School, thought her advocacy work was going to be over shortly after it began.

On Dec. 15, 2012, the day after 20 students and six educators were killed by a shooter in Newtown, Connecticut, she started a Facebook group that eventually became Moms Demand Action for Gun Sense in America.

"I have never been impacted by gun violence personally," Watts, who lives in Colorado, told ABC News. "I was just incredibly angry after the Sandy Hook shooting because I was seeing pundits on television saying the solution to the horrific tragedy there was arming teachers. And just as an American and as a mom, I knew that wasn't right."

Many, like her, thought the killing of children and teachers would be a turning point in the fight for gun control. But months later, two major pieces of legislation — the Assault Weapons Ban of 2013 and the Manchin-Toomey Amendment, which would have required universal background checks for firearm sales — failed to pass the Senate.

"I can remember thinking, 'Our work here is done. We tried really hard, and we weren't able to pass this law,'" Watts said of the Manchin-Toomey Amendment's failure.

But rather than quit the fight, she said, her group and "all of these brilliant, type-A women" who were motivated to change laws after the shooting instead "started pivoting to the states."

Taking it to the states

The state level is where the majority of the action on gun legislation has happened in the past five years. All told, since Sandy Hook, there have been 210 laws enacted to strengthen gun safety, according to the Giffords Law Center to Prevent Gun Violence.

That includes background check laws in four states that didn't have them before and expansions of existing background check laws in seven others, bringing the total to 18 states and the District of Columbia with background checks in place, according to the center.

"Now 49 percent of Americans live in states with expanded background check laws," said Avery Gardiner, a co-president of the Brady Campaign to Prevent Gun Violence.

"In some states, people are considerably safer than they were five years ago from gun violence, but that's not true at the federal level. Overall as a nation, people are dying at far too great a rate," Gardiner added.

Watts is far from alone in being motivated to act after Sandy Hook. Chris Murphy, D-Conn., was elected to move up from the House of Representatives to the Senate five weeks before the shooting. He said he was standing on a train platform on his way to Manhattan to take his young children to see the Rockettes when he learned what happened.

"My life changed in December 2012. It's not that I wasn't emotionally connected to the issues I worked on prior to Sandy Hook, but there's something different when 20 schoolkids are murdered in your backyard," he told ABC News.

"My kids were just a little bit younger than the kids that were killed, so this was personal," he added.

Over the course of the past five years, Murphy has been outspoken in his calls for gun safety. In the last 12 months alone, he has sponsored one piece of federal legislation and co-sponsored nine other bills related to guns.

But federal legislation is not where gun control advocates have seen the most success. He pointed to state-level laws, electing politicians who support tightened gun laws, and ballot referendums as meaningful ways that changes have been made.

"We've found that referendums are a very potent tool," Murphy said.

Referendums and ballot initiatives were what led to major changes in certain states, with all but one gun regulation-related measure passing.

Background checks were passed in Washington and Nevada, although the Nevada law has yet to be enacted. A referendum in California led to a number of regulation expansions, including background checks on certain ammunition purchases and requirements for reporting lost or stolen firearms. The referendum that failed was a background check measure in Maine.

"Change is going to be very hard in Washington, and I think it's likely that we're going to continue to look at referendums as a way to make change," Murphy said.

Wins for Second Amendment advocates

The 2013 failures of the Assault Weapons Ban and the Manchin-Toomey Amendment stand out as the two biggest blows to federal gun control legislation, but gun rights advocates have celebrated other legislative wins since the Sandy Hook shooting as well.

A National Rifle Association spokesperson said that while the group and its members felt that they were playing defense during the Obama administration, they now can switch to offense with the Republican majorities in the House and Senate and Donald Trump in the White House. Trump has made his support of the NRA clear, becoming the first president since Ronald Reagan to address the group as president.

Most recently, the House of Representatives passed the Concealed Carry Reciprocity Act, allowing people who have a concealed carry permit from one state to use it in all other states. The NRA hailed it as a victory on Dec. 6.

"This vote marks a watershed moment for Second Amendment rights," Chris Cox, the executive director of the NRA's Institute for Legislative Action, said in a statement.

He went on to call the act's passage in the House "the culmination of a 30-year movement recognizing the right of all law-abiding Americans to defend themselves and their loved ones, including when they cross state lines."

Aside from the Concealed Carry Reciprocity Act, an NRA spokesperson told ABC News, Trump's appointment of Supreme Court Justice Neil Gorsuch, Attorney General Jeff Sessions and Interior Secretary Ryan Zinke were all victories for Second Amendment supporters.

Gorsuch's appointment is seen as a win in that during his 2017 confirmation hearing, he called the Supreme Court's decision in District of Columbia v. Heller "the law of the land." In that case the Supreme Court ruled in 2008 that a handgun ban in Washington, D.C., stipulating that guns be kept unloaded and disassembled violated residents' rights to bear arms in their homes for self-defense. Gun rights advocates worried before the 2016 presidential election that if Hillary Clinton won, she would appoint a justice with a narrower view of the Second Amendment.

Zinke and Sessions have rolled back gun regulations in their departments.

Zinke signed an order in September that expanded hunting and fishing and types of ammunition allowed on federal lands. The order was met with praise from gun rights groups.

In October, Sessions' Justice Department narrowed the federal definition of "fugitive from justice" to apply only to people with outstanding arrest warrants who cross state lines, as opposed to those who remain in the state where they are wanted, according to a memo that has been verified by a DOJ official for ABC News.

With that narrower definition, tens of thousands of names were removed from the FBI's National Instant Criminal Background Check System, or NICS, which is used to determine whether someone is prohibited under federal law from buying firearms.

A DOJ official told ABC News that since changing the definition, the FBI's criminal justice information systems division has issued further guidance to those who input fugitive data into the background check system.

"The Justice Department is committed to working with law enforcement partners across the country to help ensure that all those who can legally be determined to be prohibited from receiving or possessing a firearm be included in federal criminal databases," the official said.

Gun control advocates, like Gardiner at the Brady Campaign, are opposed to the change to the definition of a fugitive.

"Why would you make it easier for people who are fleeing police to buy guns?" Gardiner asked.

Rate of change

Laura Cutilletta has worked at the Law Center to Prevent Gun Violence for 15 years. The group joined with former Rep. Gabby Giffords in the wake of Sandy Hook and is now known as the Giffords Law Center to Prevent Gun Violence. Cutilletta said she has noticed a definite change in attitudes about guns the last five years.

"The public, even though they've always been in support of strengthening gun laws, it hasn't always been obvious to the public just how bad our gun laws are," Cutilletta told ABC News. "So when Newtown happened, people couldn't help but notice because it was such a horrific event, and people became more educated, more aware, and became mobilized to do something about it."

That was the case for Watts, whose group, Moms Demand Action for Gun Sense in America, now has 4 million members and chapters in each state.

And it was the case for Murphy.

"I'm embarrassed by the fact that I didn't work on the issue of gun violence before Sandy Hook," he said, adding that it makes him want to "kick himself" for not acting on the issue sooner.

"My eyes were opened to the broader epidemic after Sandy Hook," Murphy added.

Correction: A previous version of this story misstated the name of Watts' group. It is Moms Demand Action for Gun Sense in America.