Self-defense becoming a more common claim in homicide cases

In a new article by the Wall Street Journal, it looks like self-defense is becoming a more common claim in U.S. homicide cases.

It's most common in states with "Stand Your Ground" laws. That law has come into focus over the past few weeks as outage continues over the death of Trayvon Martin. 

His killer claims martin attacked him and he acted in self defense.  The article said justifiable homicides almost doubled from 2000 to 2010.