1. Oklahoma is the only state which offers this method
2. 'Shot at Dawn'
3. Coup de grace

Execution by firing squad is traditionally associated with military efforts. In the event that both lethal injection and electrocution are held unconstitutional, Oklahoma is the only state which offers this option. Also known as the 'Shot at Dawn,' this method is usually performed at first light. The coup de grace is known as the use of a single bullet to the back of the head, which is specifically used if the first round was ineffective.