It used to be that people threatened with violence had a duty to flee, unless they were defending their own homes. Now 25 states have extended the right to "defend the castle" to any place it's legal to be, and anyone who claims to "perceive" a threat has the right to use equal force for protection. Florida adopted the first so-called "stand your ground" law in 2005. The Trayvon Marin case has brought attention to the laws that give people with no law enforcement authority the right to make instant decisions about life or death — with immunity from prosecution. Is that really what the Second Amendment is all about?