NEW YORK, April 4 (Reuters) - To mix metaphors, Stand Your Ground is no Slam Dunk.

The controversial 2005 Florida law grants immunity to people who use deadly force in self defense. In the days since George Zimmerman shot and killed 17-year old Trayvon Martin, critics and supporters both seem to have assumed that if Zimmerman is charged, he could easily seek and win immunity from prosecution under Stand Your Ground.

But don't be so sure. Interviews with nearly a dozen veteran defense lawyers who have experience litigating Stand Your Ground cases suggest winning immunity could be quite difficult.

"Judges do not readily grant these (immunity) motions because they know they can pass it on to the jury," said Carey Haughwout, the public defender for Palm Beach County.

So far, Zimmerman has not charged with any wrongdoing. A special prosecutor, Angela Corey, is still investigating the incendiary case, which carries heavy racial overtones and has stirred a national outcry.

But if charges are filed and Zimmerman does choose to seek immunity, he will face challenges at almost every stage, lawyers said.

The first hurdle will be a special evidentiary hearing in front of a judge, where Zimmerman will have the opportunity to argue that he deserves immunity. But to convince the judge, Zimmerman will have to present a "preponderance of evidence" that he acted in self defense, which under the law means he has to show he had "reasonable belief" that such force was necessary. That is a high bar, and difficult to prove, criminal defense attorneys said.

In cases where the facts are in dispute -- and even if they don't seem to be -- the judge is likely to deny the Stand Your Ground immunity motion, said Ralph Behr, a Florida criminal defense attorney who has filed eight motions for immunity, all of which have been denied. More typically, a judge will choose to have the case go to trial, where the defendant must take his or her chance with a jury, just like other criminal defendants, he said.

"Most judges, I think, are comfortable letting the adverserial system play out before a jury rather than make decisions themselves," said Behr.

Maggie Jo Hilliard, an attorney in Atlantic Beach, Florida, thought she had made a good argument for immunity in the case of 18-year-old Rashad Martinez. The former juvenile inmate had been charged with murdering another former inmate, 19-year-old Tremayne Lovett, and in a motion for immunity under Stand Your Ground, Hilliard cited previous incidents in which Lovett beat up Martinez. She also presented a eyewitness to a confrontation preceding the shooting who believed that Lovett was carrying a gun.

But a judge denied Hilliard's immunity motion in 2010, and after a trial, Martinez was convicted in sentenced to life in prison in February. "I can say I disagree with the jury but it does me no good. I have to trust in the system of justice that we have," said Hilliard.

The Stand Your Ground evidentiary hearings have other risks, as well. Some defense lawyers don't file such motions on the grounds that the hearings give the prosecution an advance preview of the defense's case.

"You're basically conducting a mini trial," said Christopher Frey, a defense attorney in New Port Richey, Florida. "You're putting your cards on the table before you pick a jury."

Before Florida passed the Stand Your Ground in 2005, people were allowed to protect themselves while in their homes and were not required to retreat. The law extended that right to individuals who are attacked in "any other place where he or she has a right to be." While there is no comprehensive data on how many times judges have denied such immunity motions, a review of newspaper accounts and public records by the Tampa Bay Times published last month showed judges have granted immunity just nine times since 2005.

Stand Your Ground does confer some procedural advantages to defendants that aren't available in most criminal cases. Typically, defendants accused of a crime have just one shot to avoid a trial through a motion to dismiss. If there are factual disputes between the government and the defendant, a judge is required to deny the motion without a hearing and allow the case to proceed to trial before a jury. But with the Stand Your Ground law, a defendant has the right to the evidentiary hearing, where the judge has to make factual determinations.

The guarantee of that hearing has made Stand Your Ground popular with defense lawyers. They say the hearings help protect innocent defendants from the ordeal of a trial, but more importantly, give defendants two opportunities to avoid prosecution.

"You get two bites at the apple," said Florida criminal defense attorney James Felman.

But the "preponderance of evidence" standard defendants must clear puts the burden on the defendant. After losing an immunity motion for for one his clients who had been charged with aggravated assault, Orlando defense attorney Mark Horwitz argued to a Florida appeals court that burden should be on the prosecution to prove that the defendant did not act in self defense. The court disagreed.

"Placing the burden on the defendant defeats the purpose of the statute," he said.

(Reporting by Andrew Longstreth)

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