Gun control advocates and President Obama will be pleased about Wednesday's bipartisan compromise broadening criminal background checks for gun sales. Opponents criticize the move, suggesting it wouldn't have prevented several high profile mass shootings. Indeed, of the 30 incidents since 2003 that we looked at, the Senate deal would quite possibly only have stopped one.
The compromise, between Senators Joe Manchin of West Virginia and Pat Toomey of Pennsylvania, would introduce and expand criminal background checks at gun shows and for online sellers. The NRA expressed its opposition to the bill, indicating that it wouldn't have "prevented the tragedies in Newtown, Aurora, or Tucson." In an overview of typical objections to expanded background checks, ABC News also noted the common argument that criminals don't submit to background checks.
Both of those arguments are true. Both are also very narrow.
We decided to look at what recent history actually shows. Largely relying on Mother Jones's guide to mass shootings, we identified 30 incidents over the past decade, stretching back to July 2003. (The magazine's definition requires a lone shooter who killed three or more people in a public place. We added one incident: the 2012 high school shooting in Chardon, Ohio.) We looked at how the weapons used in each incident were acquired, and, to the extent possible, the psychological and criminal history of the shooters.