Florida's "stand your ground" law has reportedly been invoked 200 times since the state passed the statute in 2005, but it's most infamously associated with Trayvon Martin's 2012 slaying as he walked to his father's house in a gated community on a rainy February evening.
Zimmerman's defence team didn't ask for an immunity hearing under the law, but the instructions provided to jurors borrowed language from the Florida statute. The only juror to speak publicly about the case also said earlier this week that she believed Zimmerman was justified in shooting Martin because he feared for his life after following the unarmed black teen.
The not-guilty verdict handed down to Zimmerman has outraged many Americans, but there have been a host of similar, lesser-known cases in states with "stand your ground" laws throughout the union — all of them involving firearms, and many of them with startling legal conclusions.
The laws — backed by the powerful gun rights lobby, in particular the National Rifle Association — vary slightly from state-to-state. But in general, they expand the concept of self-defence to allow citizens to use deadly force if they feel threatened during a confrontation.
In some jurisdictions, "stand your ground" can only be invoked if citizens involved in deadly encounters are in their homes or vehicles. In other states like Florida, the first jurisdiction to pass such laws, citizens can be on public streets and cite "stand your ground" if they end up using deadly force in a confrontation.
In Florida, an estimated 70 per cent of defendants who have invoked "stand your ground" have gone free. So have those in other states with similar laws.
In November 2007, a 61-year-old man in Pasadena, Tex., saw two people breaking into his neighbour's home. Despite a 9-1-1 operator urging Joe Horn not to confront the burglars with his shotgun, he did so anyway, killing the men.
"I have a right to protect myself too, sir," Horn told the 9-1-1 operator before gunning down the robbers. "The laws have been changed in this country."
Horn claimed self-defence and was never charged because under the Texas "stand your ground" law, he had a right to be in the place where he'd administered the deadly force.
In Louisiana last year, a 21-year-old man, Byron Thomas, was cleared in the death of 15-year-old Jamonta Miles because he claimed he acted in self-defence when he shot at the SUV the eighth grader was riding in along with several other teenagers. The two had argued when Miles tried to buy marijuana from Thomas, but the vehicle was driving away when Thomas opened fire.
The local sheriff said Thomas feared one of the teens was going to leap from the moving vehicle and start shooting, so he decided to "stand his ground."
In Wisconsin in March 2012, an unarmed 20-year-old black youth was shot and killed by a homeowner who discovered him on his back porch late one night. According to friends, Bo Morrison was trying to evade police officers who were responding to a noise complaint about a nearby underage drinking party.
The homeowner, Adam Kind, thought Morrison was a burglar, and was never charged due to the state's "intruder's bill." That law allows citizens to use deadly force against a trespasser in their homes, businesses or vehicles.
Other cases have drawn parallels to Zimmerman's.
Another Florida man, Michael Dunn, is claiming self-defence in the shooting death of 17-year-old Jordan Davis last year. Dunn claims he shot Davis at a Jacksonville gas station in a dispute over loud music after seeing a gun in the teen's car, but police say no weapon was ever found in the vehicle.
Dunn was denied bond earlier this week.
Another case being watched with particular interest by civil rights groups involves Cordell Jude, a man dubbed "the other George Zimmerman" by some news outlets for the death of a man in April in Phoenix.
Jude goes to trial next month after the shooting death of David Adkins after the mentally disabled man walked in front of Jude's car as Jude was leaving a Taco Bell drive-through in Phoenix. Adkins was walking his dog and swung the leash at Jude when he was yelled at; Jude says he believed it was a metal pipe and shot and killed him.
Jude was free for months before finally being charged with second-degree murder. But in a twist to the Zimmerman case, Jude is black, his victim Hispanic, and civil rights activists are watching the case closely to see if Jude is convicted given Zimmerman, in the aftermath of similar circumstances, was freed.
Another "stand your ground" case in Florida has a shocking racial element. Everett Gant, a 32-year-old black man, was gunned down last September by 60-year-old Walter Butler in the sleepy panhandle town of Port St. Joe, on the Gulf Coast near Panama City.
Butler, who allegedly used the n-word to describe both the victim and a child in the neighbourhood, is seeking immunity from prosecution under "stand your ground." But prosecutors allege Butler, charged with second-degree-murder, "laid in wait" for Gant, who was coming to his house to discuss his racist comments to the neighbourhood child, before shooting him in the face.
An American Bar Association task force is currently studying the country's "stand your ground" laws. It's held three hearings so far, is planning another next month in San Francisco and will table a report next year on how the laws impact public safety.
"One of the main questions is whether or not these laws actually make a community safer," the association's Leigh-Ann Buchanan said this week. "Preliminary findings of many studies have indicated that these laws may not be effective in reducing crime, and may increase incidents of justifiable homicide."
Sybrina Fulton and Tracy Martin, Trayvon Martin's parents, are pushing for restrictions on "stand your ground" laws nationwide. The divorced couple made their first public appearances on Thursday, speaking of their dismay about the verdict on various morning talk shows.
They didn't comment when asked if they planned to launch a civil suit against Zimmerman, but their lawyer said they were considering it. If they opt to launch the suit, they'd have the opportunity to challenge the state's "stand your ground' statute.