When a child is killed in a school shooting, public outrage is swift and intense. Polls consistently show overwhelming support for measures like universal background checks and raising the minimum age for gun purchases.

But Congress rarely acts.

A new study published in the Proceedings of the National Academy of Sciences helps explain why.

In “School Shootings and the Strategic Contributions of Gun Policy PACs in U.S. House Elections,” three Stanford Law co-authors show that only fatal school shootings—not nonfatal school shootings, and not other mass shootings—trigger significant increases in campaign spending by gun policy political action committees. And those increases are highly targeted to competitive U.S. House districts, where elections are decided by narrow margins and control of the seat is most at stake. The study also shows that in the wake of a fatal school shooting, both gun rights and gun control PACs rapidly push money into these competitive U.S. House races, often neutralizing each other’s influence and blunting the electoral pressure that might otherwise push lawmakers toward reform.

The study was conducted by John J. Donohue III, the C. Wendell and Edith M. Carlsmith Professor of Law and one of the nation’s leading empirical scholars of crime and public policy; Eric A. Baldwin, a Stanford Law postdoctoral research fellow, and Takuma Iwasaki, JSM ’22, JSD ’27. Baldwin and Iwasaki served as co-lead authors.

The researchers analyzed 25 years of campaign finance data, linking every fatal K–12 school shooting since 2000 to monthly PAC contributions in U.S. House districts.

The findings shed light on a longstanding puzzle, said Donohue, an economist as well as a lawyer who is widely known for using empirical analysis to determine the impact of law and public policy.

“More than 80 percent of Americans support universal background checks,” he said. “When you have that level of consensus and yet see decades of inaction, something is interrupting the normal democratic process. Our research shows that political spending is a significant part of that story.”

“What we’re observing is behavior by organized interests engaging in threat-response mobilization,” explained Baldwin, who focuses his research on public policy, political science, and empirical legal studies particularly in the areas of money in politics, representation, organized interests, and gun policy. “Fatal school shootings create a moment of political uncertainty. Our data show that pro-gun groups treat those moments as threats, or in the case of the gun safety groups, as an opportunity to advance gun safety measures supported by large swaths of the public, and both sides react by concentrating resources where they believe electoral outcomes are most in play.”

“The landscape changed significantly after 2018,” noted Iwasaki. “Following the Parkland, Florida shooting, gun safety PACs began responding to fatal school shootings with the same kind of speed and precision that pro-gun groups had shown for years. In the most competitive districts, that means both sides are intervening at nearly the same scale and at the same time — which intensifies competition but also makes it harder for either side to translate public outrage into electoral change.”

Some of the study’s other key findings:

• Following a fatal school shooting, pro-gun PACs increase contributions to candidates in affected competitive districts by roughly 31 percent. Gun safety PACs increase contributions by about 20 percent.
• When a fatal school shooting occurs within two months of Election Day, the spikes are dramatic: contributions from pro-gun PACs increase by more than 2,800 percent, and gun safety PACs by more than 900 percent.
• The spending is concentrated in closely contested districts—those decided by five percentage points or less—where electoral outcomes are most uncertain.

The researchers found no comparable spillover effects in neighboring districts or statewide races, underscoring how tightly focused and strategically deployed the spending is.

The authors say the dynamics they identify extend beyond gun policy.

“At a broader level, this study shows how organized interests can respond to moments of crisis in ways that insulate political institutions from public pressure,” Donohue said. “Understanding that mechanism is essential not just for gun policy, but for how democracy functions when highly salient events collide with concentrated political power.”

Read the paper