In the immortal words of Steven Seagal in Above the Law, “If you’re lying, i’m gonna come back and kill you in your own kitchen.”

MIAMI – Welcome to Florida, the Sunshine State. Please avoid unnecessary arguments with locals. Starting today, they may be more inclined to shoot you – at least that’s essentially the message from a national gun-control organization as a Florida law goes into effect empowering people who feel threatened to use force, including firearms, to protect themselves.

Before, if possible, they were supposed to back down or run away.

“It’s unlike any supposed self-defense statute in America,” said Peter Hamm, communications director for the Brady Campaign to Prevent Gun Violence. “It empowers people who are on edge and have violent tendencies to presume a situation is dangerous to them that may not be.”

Proponents of the law, which was championed by the National Rifle Assn., counter that it sends an unequivocal message both to would-be assailants and innocent citizens that potential victims have the legal option of protecting themselves.

“Running away is a good way to get shot in the back, raped or otherwise harmed,” said state Rep. Dennis K. Baxley, a sponsor of the law.

Under a legal concept derived from English Common Law, known as the “Castle Doctrine,” it has been long held that people have the right to stand their ground if attacked in their home. Baxley, a Republican from Ocala, said the new legislation explicitly enshrined that principle in Florida statutes and extended the concept of a person’s “castle” to personal space in a car or anywhere else he or she is entitled to be.

“We want people to know that the law contains a presumption that they have the right to protect themselves,” Baxley said.

Previously under Florida law, people acting in self-defense outside their home or workplace were supposed to use any reasonable means at hand to escape the danger, including retreat. The new law says they can “meet force with force.”

Last spring, the legislation sailed through the Florida House on a 94-20 vote, was unopposed in the state Senate and was signed by Gov. Jeb Bush. That was despite opposition from some of the state’s police chiefs, including John F. Timoney of Miami, and a tepid reaction from the Florida Sheriff’s Assn., which, according to lobbyist Frank Messersmith, withdrew its opposition after a wording change but never actually came out in favor of the bill.

State Rep. Eleanor Sobel (D-Hollywood), one of the few lawmakers to vote against the bill, said she was worried it could turn the streets of Florida into a latter-day version of the Wild West.

“With this new law, people have an excuse to use guns and say it was in self-defense,” said Sobel. “If you get into an argument in traffic with somebody, you might assume he’s reaching for his gun, so I’ll get mine first.”

It is an argument echoed by the Brady Campaign – named after former White House Press Secretary James S. Brady, who was wounded in the 1981 assassination attempt on President Reagan.

Wayne LaPierre, executive vice president of the National Rifle Assn., said fears of Floridians turning trigger-happy were groundless.

“That’s just not what good people do,” LaPierre said. “It’s been proven that good people can use rational decisions about what’s necessary to save their life.”

Predictions were just as dire, the NRA official said, 18 years ago when Florida adopted legislation allowing citizens to carry concealed weapons in public places. The precedent was followed by many other states.

What’s more, he said, Florida may have started another trend with its recasting and broadening of the “Castle Doctrine.” NRA staff members in Washington said lawmakers in at least two other states, Michigan and Alabama, were considering similar legislation.

“I honestly think this will fly through the red [predominantly Republican] states,” LaPierre said. “I think the tailwind will push it through most of the blue [predominantly Democratic] states as well.”

More than 352,000 people in Florida can legally carry concealed weapons – they either have permits or don’t need them because they are state circuit and county judges or retired law enforcement and corrections officers.

Terry McElroy, spokesman for the Florida Department of Agriculture and Consumer Services, which issues the permits, said that there was no way to know how many people might be carrying firearms without a permit but that he doubted it was a significant number.

“It’s a pretty serious offense if you’re caught,” McElroy said.

The Brady Campaign argues that Florida’s “Shoot First Law,” as its foes have labeled it, threatens to make life in the nation’s fourth-most-populous state riskier, not safer.

To alert visitors and potential visitors, the organization is placing advertisements in newspapers in Boston, Chicago, Detroit and Britain, all major markets for Florida’s tourism industry, and plans to begin handing out leaflets to arriving passengers at Miami International Airport on Monday.

“In Florida, avoid disputes,” recommends the newspaper ad. “Use special caution in arguing with motorists on Florida roads.

“If someone appears to be angry with you, maintain to the best of your ability a positive attitude, and do not shout or make threatening gestures,” says the flier.

Hamm said it was not the intent of the Washington-based organization to harm Florida tourism, but to inform visitors and help them be safe. The Brady Campaign official said he still planned to visit the seaside town of Delray Beach with his children, 3 and 7, around Easter – “I just don’t intend to argue with anyone.”

Despite all the controversy, the law may not have expanded a citizen’s rights much at all, said Bruce Colton, a state prosecutor in Fort Pierce who is president of the Florida Prosecuting Attorneys Assn. At a meeting last winter, Colton said, he and other prosecutors couldn’t think of a single instance of a person convicted for using deadly force to protect himself or a family member in the street or anywhere else who would be exonerated by the new law.

“From a practical standpoint, it’s not going to change things,” he said.

His only concern, Colton said, is that some people might now wrongly interpret the law to mean that “if you bother me on the street, I can shoot you.”