A mass shooting takes place, followed by emotional vigils, intensive news media coverage and sorrowful statements by politicians. But what does it actually mean for laws and policies around guns?

Lots of gun laws are proposed in the aftermath of an attack, new research shows. But in terms of what actually is enacted, the results aren’t what you might expect.

In states where a mass shooting happened, 15 percent more gun-related bills were introduced in state legislatures, three Harvard Business School professors found in a working paper published last month. But in states with legislatures that were led by Democrats or divided between the parties, a mass shooting wasn’t followed by any statistically significant increase in gun laws enacted.

It was different in states with Republican-controlled legislatures. After a mass shooting, the number of laws passed to loosen gun restrictions rose by 75 percent. In other words, in places where mass shootings lead to any legislative changes at all, it tends to be in the direction of guns becoming more easily available, like lowering the minimum age to buy a handgun to 18 from 21 or eliminating a waiting period for a gun purchase.