Public outcry and vague commitments from the attorney general will likely not be enough to induce substantial changes because the federal government has little say over state law, says Jennifer Zedalis, a law professor at the University of Florida in Gainesville, Fla. and a defense attorney with 30 years of courtroom experience.
Adds State University of New York political scientist Robert Spitzer, an NRA member and author of four books on U.S. gun policy, "there is a culture, or a subculture, in some places in the U.S. that is extremely forgiving to people who take the law into their own hands."
"It's a point of view that is aggressively cultivated by politically influential pro-gun forces like the National Rifle Association," he says.- U.S. attorney general criticizes stand-your-ground laws
- Trayvon Martin's parents shocked by Zimmerman acquittal
On Tuesday, U.S. attorney general Eric Holder told the National Association for the Advancement of Coloured People that "it's time to question laws that senselessly expand the concept of self-defence."
He added that "by allowing and perhaps encouraging violent situations to escalate in public, such laws undermine public safety."
Other high-profile figures have also spoken out.
At a concert in Quebec City this week, Stevie Wonder vowed, "until the stand your ground law is abolished in Florida, I will never perform there again." He went on to say, "wherever I find that law exists, I will not perform in that state or in that part of the world."
Wonder will likely be playing fewer U.S. concerts in the coming years. About 27 states across the U.S. have adopted stand your ground-style legislation, with at least three others currently considering it.
The law says that a person has no duty to retreat and can meet "force with force" if they feel threatened, even in public spaces. Florida was the first state to pass a stand your ground law in 2005. It is also a place where approved gun permit holders are allowed to carry concealed weapons.
"At it's simplest, it's a kind of 'shoot first, ask questions later' policy," says Zedalis.
"The only way I think the feds could intervene is if they could show that there was something systematic in the legislation itself, or in the implementation of the legislation that denies constitutional rights of citizens based on race, class or ethnicity," she says.
"They probably won't get anywhere with that because it's tough to argue and tougher to prove."
NAACP president Ben Jealous has called for a Department of Justice investigation into civil rights charges against Zimmerman. But even if civil rights charges were filed in this particular case, it would likely have little impact on a broader scale, she says.
According to Spitzer, Florida's stand your ground law was enacted "very specifically at the urging, pushing and lobbying of the National Rifle Association."
"The state legislature is very friendly to the NRA and conservative forces within the state. So it was fertile ground to try this," he says.
Law enforcement officials and prosecuting attorneys opposed the bill from its inception, but lobbyists were able to push the bill into law "under the national radar," he adds.
Marion Hammer, the NRA's first female president from 1995 to 1998, and one of the state's most influential pro-gun voices, spearheaded the effort.
Hammer is well known for her lobbying success. The NRA credits her with a seven-year effort to pass concealed weapons laws in Florida.
The legislation, passed in 1987, requires the state to issue a permit to carry a concealed weapon to anyone who meets standardized criteria. There are now more than two million permits in the state and similar policy has been adopted in 39 others.
Concealed-carry laws paved the way for stand your ground says Spitzer.
"If you believe the logic of concealed-carry proponents, that civilians with a gun permit make society safer, it's only a small step to provide a little bit more legal protection to make sure the good guy with a gun is not wrongfully or maliciously prosecuted," he says.
Following the passage of the Florida stand your ground law in 2005, vice president of the NRA Wayne LaPierre told the Washington Post that it was "the first step in a multi-state strategy."
To this day, the NRA remains a strong proponent of stand your ground legislation.
Following Holder's recent comments, for example, NRA officials issued a written statement saying that Holder "fails to understand that self-defense is not a concept, it's a fundamental human right" and "to send a message that legitimate self-defense is to blame is unconscionable."
Stand your ground laws, however, have raised serious legal questions about what constitutes "legitimate self-defence."
The legislation is an extension of an older British common law called "the castle doctrine," which provides legal protection to people who use force, including deadly force, while defending their homes from an intruder.
Before stand your ground, using deadly force in self-defence outside of your home could only be justified if there was clearly "no opportunity to retreat from a threat," says Zedalis.
Since Florida passed the law in 2005, and in most other states that have adopted some form of the measure, there's no longer a duty to retreat.
In other words, "if you found yourself in a situation where you reasonably believe you're in imminent danger of death or serious bodily harm, you can stand your ground," she says.
The law in Florida is so strong that police cannot even arrest a person who claims self-defence unless investigators have "probable cause to believe the killing was unjustified," she adds.
It's often cited as the reason why George Zimmerman was not arrested until 44 days after the shooting death of Trayvon Martin. While Zimmerman's lawyers did not use stand your ground as a specific defence in his trial, the judge explicitly told the jury that he had "every right to stand his ground."
Defendants can also avoid going to trial if they successfully invoke a stand your ground defence.
"If a judge finds that sufficient evidence exists to make a finding pre-trial that a person was justified in the killing, they are immune from prosecution," says Zedalis. "That puts a very high burden on a judge and takes the case out of the hands of a jury."
Self-defence or vigilantism?
As more stand your ground cases pile up across the U.S., data is emerging about their impact on homicide rates and successful prosecutions.
According to an investigation by the Tampa Bay Times, rates of "justifiable homicides" – where a judge has vacated a murder charge in the preliminary hearings – nearly tripled from 2005 to 2010.
In a later review of 200 stand your ground cases, the newspaper found that nearly 70 per cent of defendants who claimed the provision in pre-trial hearings went free despite the fact that 135 of the slain victims were unarmed during the confrontation.
In nearly a third of the cases, "defendants initiated the fight, shot an unarmed person or pursued their victim – and still went free," says the article from June 2012, four months after the deadly Zimmerman-Martin confrontation in February.
Similarly, a 2012 study from Texas A&M University found that stand your ground had failed to deter crime rates, and had actually added from 500 to 700 homicides a year across all of states with similar laws.
The numbers have caused "a lot of public concern over vigilante justice," says Zedalis. "People taking the law into their own hands, racial profiling, and the risk that innocent people are being shot and killed, and the shooter gets the benefit of the doubt."