Florida's notoriety as the "shoot first" state grows by the day. As its citizens pull guns on one another at gas stations and on basketball courts, at birthday parties and in movie theaters, the perception grows that the state's 2005 "stand your ground" law made it a safe haven for killers. • But like many caricatures of the Sunshine State, this one is too simple. The truth is that Florida did not pioneer the controversial rules of justifiable homicide it adopted nine years ago — though the rules' effects here might serve as a warning for other states. • The debate over "stand your ground" laws has never been more urgent than in the last eight months, a period in which Florida juries have twice delivered verdicts in heavily publicized murder trials that ignited the scorn of gun control and civil rights activists.

The July 2013 acquittal of George Zimmerman and the conviction on lesser charges last month of Michael Dunn — each had fatally shot a black teenager — renewed criticism of the laws, which erased the duty to retreat from violent confrontations.

Critics as prominent as U.S. Attorney General Eric Holder argue that such statutes, enacted by legislatures in Florida and 21 other states under pressure from the National Rifle Association, have emboldened gunmen and made it harder to bring them to justice once they are caught.

In a speech to the NAACP in Orlando last year, Holder spoke of "the commonsense and age-old requirement that people who feel threatened have a duty to retreat, outside their home, if they can do so safely."

Yet a look back at American history shows that requirement has not been viewed as "commonsense" in large swathes of the nation for a century or more. Long before the first NRA lobbyist roamed the halls of a state capitol, the duty to retreat had been quietly eliminated in jurisdictions from Illinois to Colorado through case law — the judicial interpretation of often ambiguous self-defense statutes.

In addition to the 22 states that have enacted "stand your ground"-type statutes in the past two decades, an additional nine have established through case law that there is no duty to retreat, according to an analysis by the Tampa Bay Times. Combined, those "case law" states are home to 79 million people, about a quarter of the U.S. population.

"In the last couple of years the NRA has pushed a lot of restrictions," Boston University School of Law professor Kenneth Simons said. "But even before that push, there were a lot of states that either recognized no duty to retreat, or recognized it only in very narrow circumstances."

Some critics of Florida's law have also focused on its requirement that citizens must have a "reasonable belief" in a threat before using deadly force, not that the threat actually exist. But in this regard, Florida is even less of an outlier.

The idea that "reasonable belief" in a threat justifies homicide prevails throughout the country, according to legal experts. It is not, as some observers have claimed, carte blanche for killers to act on ungrounded fears, but a test of what an ordinary, rational person would do in the same circumstances.

"It's one of the most invoked terms in the law," said Saul Cornell, a professor of American legal history at Fordham University. "The original notion of 'reasonable' often gets lost. 'Reasonable' is actually a pretty high standard."

Unlike states where similar changes were achieved through high-profile legislative battles, those in which "stand your ground"-style rights were enshrined by case law have mostly escaped the attention of reporters and activists.

California, for example — the most populous American state, with the nation's strictest gun laws — is rarely mentioned in the debate over self-defense law.

But the California Supreme Court empowered its citizens to stand their ground and use deadly force in public places about 120 years ago, a precedent reflected to this day in the state's jury instructions. One instruction states not only that "a defendant is not required to retreat" and "is entitled to stand his or her ground," but that she is allowed, "if reasonably necessary, to pursue an assailant."

In other words, a Floridian may stand his ground. But a Californian, under the right circumstances, can chase his attacker.

'He may stand his ground'

The idea that someone under threat or attack has a duty to retreat dates at least as far back as the Middle Ages. English monarchs sought to solidify their grip on a rudimentary nation-state by reserving for themselves the right to kill — a corrective to rampant murder and blood feuding in a populace with little experience of the rule of law.

The imperative to "retreat to the wall" at one's back before turning to fight was incorporated into the English common law and imported during the colonial period to America's Eastern Seaboard. But as settlers spread west of the Appalachian Mountains, the right to "stand one's ground" and use deadly force gained currency in frontier states and, increasingly, among those states' judges.

Perhaps the strongest articulation of "no duty to retreat" came not from a state judge but from one of the foremost jurists in U.S. Supreme Court history: Justice Oliver Wendell Holmes.

In 1921, the high court overturned the conviction of Robert Brown of Texas. While working on a construction site, a co-worker threatened Brown during an argument about whether a pile of dirt should be moved. Brown ripped a handgun from his coat and shot the man four times.

Holmes did not disapprove.

"Many respectable writers agree that, if a man reasonably believes that he is in immediate danger of death or grievous bodily harm from his assailant, he may stand his ground," Holmes wrote in his opinion for the majority. He memorably affirmed the "reasonable belief" standard in justifiable homicide, writing that "detached reflection cannot be demanded in the presence of an uplifted knife."

By the time Holmes handed down his opinion, the "American theme of no duty to retreat ... had been written into the common law of a majority of American states," historian Richard Maxwell Brown writes in his seminal 1991 study of American self-defense laws, No Duty to Retreat: Violence and Values in American History and Society.

A minority of states, skewed toward the Northeast, nevertheless retained the English common law's dim view of public confrontations. Before 2005, that group still included one large and increasingly well-armed member: Florida.

Zimmerman in Chicago?

The raft of 2005 statutory changes known as Florida's "stand your ground" bill went beyond the changes wrought elsewhere by case law. Perhaps the most significant difference was a new procedure for homicide defendants to ask a judge for immunity from prosecution before a trial begins.

The law also discouraged police officers from making arrests and prosecutors from bringing cases in the first place, said Laura Cutilletta, senior staff attorney at the Law Center to Prevent Gun Violence.

"One of the main differences is that in Florida, the 'stand your ground' law comes into effect even before the arrest is made," Cutilletta said. "It can deter the arrest and the prosecution."

But as a case goes before a jury these differences begin to vanish.

Judges in states where legal precedent rejects the duty to retreat sometimes have more leeway on whether to instruct a jury that self-defense is an issue in a murder trial. But if the instruction is given, it doesn't differ much from what juries hear in states with "stand your ground" legislation.

The jury in Zimmerman's case was instructed that "he had no duty to retreat and had the right to stand his ground and meet force with force, including deadly force" if he "reasonably believed that it was necessary to do so to prevent death or great bodily harm to himself."

In Illinois, jurors would have been told that Zimmerman's fatal shooting of Trayvon Martin, an unarmed teenager, was justified if Zimmerman "reasonably believed" such action was necessary and that he had "no duty to attempt to escape the danger before using force," according to the Illinois Supreme Court's pattern jury instructions.

"His defense was that he thought his life was in danger, and in Illinois, there's no duty to retreat," Damon Cheronis, a Chicago criminal defense attorney, said of Zimmerman. "I don't think it would have gotten a different shake in Chicago."

Alan Malott, a judge in the second judicial district of New Mexico — which has no equivalent of Florida's law, but where the duty to retreat was removed by the state Supreme Court half a century ago — likewise said he doubted Zimmerman's trial would have had a different outcome in Albuquerque.

"I think if you tried it 10 times, nine times you'd probably get a consistent verdict," Malott said.

More guns, other factors

The fact remains that neither New Mexico, Illinois nor California have had homegrown versions of the Dunn or Zimmerman cases in recent years.

Curtis Reeves, likely the next lead actor in a "stand your ground"-inflected legal drama, made headlines in Pasco County, not Los Angeles. A retired Tampa police officer, Reeves is charged with second-degree murder for shooting a man he had upbraided for sending text messages in a movie theater.

The publicity that accompanied the passage of Florida's law might have brought a kind of glamor to justifiable homicide that is absent in states where a virtually identical legal standard was forged with less fanfare, said Jim Hammer, former lead prosecutor in the homicide division of the San Francisco District Attorney's Office.

"The truth is, on the letter of the law, California is not much different from Florida," Hammer said. Nevertheless, the political rhetoric that accompanied Florida's overhaul of its self-defense laws, he said, sent "the message that it's a little safer to use a gun in Florida than in California."

A message for policymakers, perhaps, is that the mere language of "stand your ground" statutes is not to blame for bloodshed.

An analysis of national crime data by the Guardian newspaper found that on their own, "stand your ground" statutes "cannot be statistically linked with the rise in justifiable homicides" across the United States. However, the newspaper found that "in states with both SYG laws and the weakest gun controls" there exists "a statistical correlation with an increase in justifiable homicides."

Florida is an undisputed outlier in one measure of permissive gun laws — the number of concealed weapons licenses it issues. As of February 2014, Florida had issued 1.4 million permits to carry a concealed firearm, or about one for every 14 residents. Zimmerman and Dunn were licensees. Reeves, as a retired cop, was allowed to carry a concealed gun in public.

By contrast, until recently Illinois banned the carrying of concealed guns altogether, and California, which strictly regulated the permits, issued one for about every 25 distributed in Florida.

But those states' lightly armed status quo is changing.

Last month, the U.S. 9th Circuit Court of Appeals struck down California regulations giving counties broad authority to deny permit applications, leading to a surge in requests. This month, Illinois' first concealed-weapon licenses are arriving in their owners' mailboxes as a new law that allows the carrying of guns in public takes effect.

"It's going to be interesting to see how the great citizens of Cook County are going to react to that," Cheronis said.

Florida might have been a latecomer in abolishing the duty to walk away from a fight. But in illustrating how such rules of engagement affect an urban society glutted with deadly weapons, it could offer other states a window on their future.

News researcher John Martin contributed to this report. Peter Jamison can be reached at pjamison@tampabay.com or (813) 226-3337. Follow him on Twitter @petejamison.