The number of justifiable killings committed by police and private citizens has been trending upward over the past decade, rising in 2009 to their highest levels in more than a dozen years in both Virginia and the nation. There are no definitive answers to what is causing more law-enforcement officers and individuals to use deadly force in dealing with crime. But some criminologists say changing attitudes about the circumstances in which lethal force can be used in... (GunPolicy.org)