The Florida law, passed in 2006, says people who feel threatened don't have to retreat from danger, no matter where they are. And it became a huge point of contention after Zimmerman's arrest, with his supporters saying the incident demonstrated the precise need for the law and critics saying it encourages a "Wild West" or vigilante mentality.

But Zimmerman's lawyers say it doesn't apply to his case, at least not exactly.

"In this particular case, George did not have an ability to retreat because he was on the ground with Trayvon Martin mounting him, striking blows, therefore the Stand Your Ground 'benefit' given by the statute simply does not apply to the facts of George's case: it is traditional self-defense," Zimmerman's attorneys said on the web site detailing his legal case.

But they do intend to ask a judge to apply the immunity provisions of Florida's self-defense law to stave off a trial on the charges.

The law says people who use fatal force within the guidelines set out by the law are immune from prosecution.

A hearing on the issue could happen in April, according to the web site.

5. Trayvon Martin would have celebrated his 18th birthday this month

Martin would have turned 18 on February 5.

His supporters marked his birthday with a peace rally in a historically black part of Sanford in central Florida, CNN affiliate WFTV reported.

It was a relatively small affair, about 70 people, compared with the thousands who turned out regularly to support Martin's family and demand Zimmerman's prosecution in the weeks immediately after his death. Those rallies, led oftentimes by civil rights leaders from around the country, helped catapult the case into the national limelight.

Unlike early demonstrations, where supporters issued loud and relentless calls for justice, the Sanford birthday ceremony was more subdued.

This time, supporters wore bracelets reading "Band Together," WFTV reported, and called for healing in the community after the shooting, which divided black and white residents and put the police department in a harsh light for not immediately arresting Zimmerman.

"There's something coming out of this, and that's understanding. Sanford will be a better community for it," said lawyer Natalie Jackson, who was among those representing the Martin family in the spring.

Two people who were front and center at those earlier rallies -- Martin's parents, Sybrina Fulton and Tracy Martin -- were not in Sanford that day. Instead, they quietly and privately marked their late son's birthday in Miami, WFTV said.