Mass shootings lead to a spike in new state gun laws. Whether the laws tighten or loosen curbs on guns laws depends on the dominant political party in the state. Harvard Business School researchers Deepak Malhotra and Chris Poliquin found 3,211 new state gun laws between 1990 and 2014, NPR reports. After mass shootings, Republican-dominated states tend to loosen gun restrictions and Democratic states more likely tighten them.
For example, Democratic Gov. Jerry Brown of California just signed six gun-control bills into law, many in response to the mass shooting in San Bernardino in which 14 people were killed. In Tennessee, where last July, a gunman killed four people and injured three more at a military recruiting station and a Navy building in Chattanooga, among new laws passed is one that allows full-time employees of public universities to carry handguns on campus. There is little research that shows how specific gun laws influence gun violence, NPR says.