This story was published in partnership with the Trace.

Two weeks before Christmas in 2012, a 22-year-old masked man armed with a stolen assault-style rifle went on a shooting rampage in a crowded shopping mall in Happy Valley, Oregon, just outside Portland, thrusting holiday shoppers into a maelstrom. By the time the bullets stopped flying, three people, including the gunman, had been fatally shot, and a 15-year-old girl was wounded.

Now family members of the deceased victims are pushing for a ballot measure that would make Oregon one of the few states in the nation to mandate that gun owners lock up their firearms. They contend that such a law could have thwarted the afternoon massacre at the Clackamas Town Center mall.

"People want to do something." —Jenna Yuille

The longshot measure offers another example of how supporters of stricter gun laws are trying to harness the collective outrage generated by the more recent mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida, that left 17 people dead and 17 injured.

“People are fed up, and they don’t want to wait around to see what their legislature is going to do,” said Jenna Yuille, whose mother, Cindy, 54, was one of the shoppers killed in the Clackamas mall. “People want to do something.”

That urge for action has upended gun politics in statehouses around the country as elected officials face mounting pressure to impose tighter restrictions on firearms. The latest development came on Wednesday in Vermont, where Governor Phil Scott approved a slate of new laws that would, among other things, allow guns to be seized from potentially dangerous people, expand background-check requirements for gun sales, and ban high-capacity ammunition magazines.

In an election year, ballot measures give advocates an alternative route to reform, especially when recalcitrance by state lawmakers on a given policy change is predicted. The gun storage requirement is one of two gun-safety ballot measures brewing in Oregon, while a group in Florida is gearing up to put an assault weapons ban before voters in 2020. Oregon voters have successfully sidestepped legislative opposition on the gun issue at least once before, in 2000, when they approved extending background checks for firearm sales at gun shows.

The measure that Clackamas survivors are now pushing would enact a so-called safe-storage law, under which gun owners would have to lock up firearms not under their direct control. The measure would also require anyone whose guns are lost or stolen to report the incident to law enforcement within 24 hours.

Violations of either provision could result in fines—reaching up to $2,000 if a child picked up the firearm—and expose gun owners to civil liability if their purloined weapons are used to injure someone within five years.

The other gun-related question that Beaver State voters may decide on Election Day would ban the sale of assault-style rifles and magazines capable of holding more than ten rounds of ammunition. Although both initiatives have momentum, opponents may lodge court challenges, during which organizers must pause signature-gathering. Proposed initiatives must have more than 88,000 backers by July in order to qualify for the November ballot.

As with many areas of gun policy, the research on firearm-storage laws is scant, though they have been linked to declines in unintentional gun injuries and suicides among young people.

They may also be an effective means of curbing gun theft, a growing problem in Oregon. In 2016, at least 2,734 guns were reported stolen in the state, the highest figure since 2008, according to data from the National Crime Information Center, a federal database used to track stolen property. All told, more than 24,000 guns have been stolen in Oregon over the last decade.

As The Trace has previously documented, stolen firearms pose a potent public safety threat. Between 2011 and 2016, about 10 percent of the more than 3,600 guns recovered by Portland Police from crime scenes and other circumstances had been stolen, according to data obtained through a public records request. That number is likely an undercount: many gun thefts are never reported, and even when they are, victims often do not know the serial numbers to their guns, making it difficult for authorities to tie them back to a crime.

There are four states with some version of a safe-storage law, and 11 with a lost-and-stolen reporting requirement. Numerous cities around the country—including Portland—have enacted their own safe-storage or lost-and-stolen reporting measures.

Critics of these mandates argue that they penalize gun owners for the actions of criminals and could prevent people from being able to access their weapons in the event of an emergency.

Kevin Starrett, who leads the Oregon Firearms Federation, has lambasted the proposed measure, telling the Portland Tribune that gun owners should be able to store their weapons in whatever way comports with their personal circumstances.

“This is not how you solve the problem of people who use guns in a criminal fashion, by punishing people who don’t use guns in a criminal fashion,” Starrett told the Tribune.

In the days leading up to the Clackamas Town Center mall shooting, the gunman, Jacob Tyler Roberts, stocked up on magazines and ammunition from local stores. Early on December 11, 2012, he went over to a friend’s house to drink, play pool, and smoke pot. While they were hanging out, the friend, Sean Cates, showed Roberts his Stag Arms semi-automatic rifle.

Later, Roberts fell asleep on Cates’s couch. The next morning he woke up, took the rifle, and drove over to the mall, where he commenced his rampage. Law enforcement officials said the death toll may have been higher had the rifle not jammed.

Paul Kemp, whose brother-in-law, Steven Forsyth, 45, was among the Clackamas victims, said he was astounded to learn that Cates could not be held responsible for leaving the rifle where it could be taken and for not reporting the theft until after the shooting. He was further disheartened in 2015 when the state Senate failed to advance a bill that would have made it a crime to leave unsecured guns around children, a more modest version of the storage measure he is advocating.

Even if the safe-storage measure fails this year, Kemp said he hopes to gather enough support that state lawmakers take notice.

“There’s no appetite by some of the legislative leadership to bring gun bills forward unless the gun-violence prevention advocates make it so difficult for them they can’t ignore it,” said Kemp, himself a gun owner who, along with Yuille, helped found the group Gun Owners for Responsible Ownership.

“They’ve had 20 or 30 years to fix this stuff, and they’ve chosen not to do a damned thing.”