Voluntary manslaughter is a killing, derived from an intentional act in the heat of passion or provocation.

Involuntary manslaughter is an unintentional killing resulting from recklessness or negligence. A drunk driver hitting a child or a person, thinking a firearm is unloaded, shooting a friend are examples of involuntary.

If Zimmerman grabbed his weapon and formed an intent to shoot Martin in their scuffle, then voluntary would be more appropriate. If the jury feels that his use of the firearm was reckless, but unintentional, then involuntary may be considered.

To be exculpated Zimmerman must establish self-defense, which is a reasonable belief that he was in danger of losing his life or receiving serious bodily injury. This defense is not available if the jury determines that Zimmerman participated in some way of causing the physical confrontation that resulted in the shooting.