The shooting of U.S. Rep. Gabrielle Giffords last January raised questions about the effectiveness of gun laws—whether they keep guns out of the hands of criminals and prevent crimes. It was tempting to point a finger at Arizona’s gun laws as too weak, and somehow responsible for the shooting of Giffords, who is still undergoing intensive rehabilitation after a gunshot wound to the brain.

Arizona allows guns in bars and has broad “concealed-carry” provisions, but its gun laws mostly reflect federal law. “Look at Arizona as an example of what can happen anywhere,” Garen Wintemute says. He has been studying gun violence and efforts to prevent it since the 1980s, and he has come up with some striking findings. A change in California’s gun laws allowed him to compare two similar groups of people—one that was able to purchase guns, and another that wasn’t. The group that had a tough time getting guns had a 25% to 30% reduced risk of committing a crime. As part of Wintemute’s recent research, he did undercover work at gun shows, to which he carried a hidden camera. He will give us an update on gun-control research, what we can expect in coming years, and whether tougher gun laws could prevent future shootings like that of Gabrielle Giffords. For more information...