Protest in New York City’s Union Square against the killing of Trayvon Martin. Francis Reynolds/The Nation

Former Florida Governor Jeb Bush endorsed Mitt Romney Wednesday, earning national headlines as an elder statesman of a Grand Old Party that is still trying to wrap its head around the concept of Romney as a presidential nominee.

It is a measure of the extent to which media and political players absolve those who make laws from any responsibility for the impact of the legislation they enact and sign that Romney—who has so meticulously avoided discussing the Trayvon Martin killing in Florida—would casually accept the backing of the signer of the “Stand Your Ground” law that so many reasonable observers believe played a role in Trayvon’s death.

The 17-year-old Florida youth was apparently hunted down and shot by a “neighborhood watch” gunman while Trayvon was returning from a trip to a nearby 7-11 store. The gunman, George Zimmerman, was reportedly of the belief that he had been given what was effectively a license to kill by Florida’s “Stand Your Ground” law. Police in Sanford, Florida, apparently shared that view, as they decided against arresting and charging the shooter.

The Florida “Stand Your Ground” law was enacted in 2005 with bipartisan support by Republican-controlled houses of the legislature. The National Rifle Association led the advocacy on behalf of the proposal, arguing that it was needed to provide immunity to gunmen who might use deadly force against unarmed individuals who they imagine to be threatening.

The “Stand Your Ground” legislation was sponsored by Florida state Representative Dennis Baxley and state Senator Durell Peadon, both Republican ally of Jeb Bush. The governor quickly signed the measure into law—despite explicit and repeated warnings that this law would encourage shootings of innocents like Trayvon Martin. And despite explicit and repeated warnings that people of color and young people would be unreasonably and disproportionately harmed by the law.

Baxley and Peadon worked closely with NRA lobbyist Marion Hammer to pass the Florida law, and Hammer appeared with Bush at the signing ceremony.

But the process did not stop on Tallahassee, where the vote was taken.

Baxley and Peadon served in the Florida House and Senate as active members of the American Legislative Exchange Council (ALEC), the shadowy Koch brothers–funded network that brings together right-wing legislators with corporate interests and pressure groups to craft so-called “model legislation.”

For the most part, ALEC’s model legislation is designed to ease taxes and regulations for corporations, while weakening unions and undermining tort laws. But the council also dabbles in electoral and public safety issues. And “Stand Your Ground” proposals were added to the agenda after Baxley and Peadon passed the Florida law seven years ago.

Only a few months after Bush signed the Florida law, Hammer worked with NRA operatives and friendly legislators on ALEC’s “Criminal Justice Task Force” to develop a new piece of “Stand Your Ground” model legislation for passage in states across the country.

The proposal made a strong impression on ALEC members, who approved model legislation that mirrored the Florida law’s assertion that an individual gunman or a neighborhood watch member “has no duty to retreat and has the right to stand his or her ground and meet force with force, including deadly force if he or she reasonably believes it is necessary to do so to prevent death or great bodily harm to himself or herself or another, or to prevent the commission of a forcible felony.”

In states across the country, with support from the gun lobby, ALEC’s model legislation—sometimes in mirror form, sometimes with modest alterations—has been enacted over the years since Peadon and Bush dismissed the warning by Florida state Senator Steve Geller that the “Stand Your Ground” law ran the risk of encouraging Floridians to think that “you ought to be able to kill people that are walking toward you on the street because of this subjective belief that you’re worried that they may get in a fight with you.”

Similar arguments were made in state after state, as ALEC members—acting with encouragement first from the Criminal Justice Task Force and more recently from the Public Safety and Elections Task Force (which has in recent years been staffed by a “Koch Associate” through the Charles G. Koch Charitable Foundation)—introduced, advocated for and passed not just "Castle Doctrine" laws (which allow for the violent defense of homes) but “Stand Your Ground” laws (which extend home-defense principles into the streets).

According to the Center for Media and Democracy, which worked with The Nation on the ALEC Exposed project, “Since becoming an ALEC model, sixteen states have passed laws that contain provisions identical or similar to the ALEC ‘Castle Doctrine Act.’ In 2007 it was passed in four states and highlighted by ALEC on their ‘legislative scorecard.’ ”

In those states, as in Florida, the number of so-called “justifiable homicides” is on the rise. Florida Department of Law Enforcement suggests that the number of justifiable homicides in the state have tripled since Jeb Bush signed the “Stand Your Ground” law.

Why? Former US Attorney Kendall Coffey tells NBC, “The ‘Stand Your Ground’ law is a license to kill.”

“The ‘Stand Your Ground’ law has become a huge obstacle to preventing exactly this kind of self-appointed vigilantism—this kind of vigilante justice,” says the veteran federal prosecutor. “It used to be if you shot somebody in quote-unquote ‘self-defense,’ you were protected. But in 2005, Florida decided to become the pioneering state to extend this kind of self-protection to wherever the heck you go…”

Florida, under Jeb Bush, was the pioneer. But, now, thanks to the American Legislative Exchange Council, it is just one of many states that offers gunmen that license to kill.

For more on the investigation of the American Legislative Exchange Council by The Nation and the Center for Media and Democracy, go to “ALEC Exposed.”

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