Zimmerman killed Travon = fact
The legal charge is murder ( which implies premeditation).
In a legal charge, self-defense is a legal defense (deadly physical force used to prevent deadly physical force).
It is a universal legal principle
The “ Stand Your Ground “ is a legal defense precedent in certain jurisdictions , but not in all . This precedent could have been used in this incident
The “ Castle Doctrine “ is a legal defense precedent in certain jurisdictions , but not in all