Why the U.S. has done almost nothing to stop mass shootings

The violence in Oregon is one of nearly a thousand mass shootings to have taken place since the Newtown shooting in 2009. For all of the discussion of what can be done to prevent future tragedies, little has changed. What can be done to stop the violence? Judy Woodruff talks with Todd Clear of the Rutgers School of Criminal Justice and Jeffrey Swanson of Duke University.