Neighbourhood watch volunteer George Zimmerman pleaded not guilty to charges that he murdered unarmed teenager Trayvon Martin on February 26.
His lawyer Mark O'Mara said Mr Zimmerman would invoke Florida's controversial "stand your ground" law, which grants killers immunity if they use deadly force in self-defence.
Mr Zimmerman was charged with second-degree murder on Wednesday, two months after he admitted shooting Mr Martin.
He handed himself in shortly after Florida prosecutor Angela Corey announced the charges. He faces life in prison if convicted.
Mr Martin's parents and civil rights groups including the National Association for the Advancement of Coloured People (NAACP) led a 45-day campaign for Mr Zimmerman's arrest.
NAACP president Benjamin Jealous welcomed the charge but said it "is just the beginning."
The US must "address the issues of racial profiling and the valuation of black men's lives by law enforcement," he said.
"In the months ahead the NAACP and our allies in the civil rights community will continue to take these issues on as well as the urgent need to repeal the 'stand your ground' law."
New York City Mayor Michael Bloomberg on Wednesday called the law "a licence to murder."
It allows people to "meet force with force, including deadly force" if they feel that their life is in danger or that they could be seriously wounded.
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