When George Zimmerman shot and killed unarmed 17-year-old Trayvon Martin in February, Zimmerman -- who considered himself a neighborhood watchman -- almost certainly thought of himself as a "good guy."

In November, 45-year-old Michael David Dunn likely thought he was playing the role of the "good guy" when he confronted a vanload of teenagers for playing their music too loud, then fired nine shots into their vehicle after claiming he saw a shotgun barrel. 17-year-old Jordan Russell Davis was killed, and neither Jordan nor anyone else in the van had a gun.

"The only thing that stops a bad guy with a gun is a good guy with a gun," said National Rifle Association CEO Wayne LaPierre in the organization's first news conference after the Newtown, Connecticut massacre. The NRA's solution to mass shootings is not fewer guns or even safer guns, but more guns -- as long as the "good guys" are packing, their reasoning goes, the "bad guys" can't do much damage.

But the notion of "good guys" and "bad guys" is a severe oversimplification in most incidents involving gun violence.

Many Americans -- and certainly the mothers of Trayvon Martin and Jordan Russell David -- would say that Zimmerman and Dunn were indeed the "bad guys," using excessive force in response to the imagined threat posed by unarmed teenagers.

Stand Your Ground, or Kill at Will?

LaPierre's statements came in the context of the Newtown school shooting but the NRA has long supported the notion that gun violence is cured by more guns. The NRA has not only advanced the morally reductive "good guy vs bad guy" portrayal of gun violence as a rhetorical tool, but has gone further, successfully lobbying for legal protections for self-styled "good guys" who shoot to kill.

As the Center for Media and Democracy (CMD) has reported [3], the NRA-conceived (and American Legislative Exchange Council-ratified) "Stand Your Ground" laws give license for people to engage in vigilantism without liability.

Police initially cited Florida's Stand Your Ground law to avoid arresting Zimmerman, and only took him into custody after weeks of public outcry. Dunn reportedly will invoke the Stand Your Ground law at trial.

The NRA's Stand Your Ground bill goes far beyond the traditional right to claim self defense by establishing a legal presumption of criminal and civil immunity when a shooter claims they were threatened, whether in the home or in a public place. As Madison police officer Brian Austin explained [4] earlier this year, legal protections already existed for those who used force to protect their home, but what the Stand Your Ground law does "is essentially remove the requirement that a person actually evaluate whether the person they shoot is presenting an imminent threat of death or great bodily harm." The law creates an environment where armed individuals are emboldened to use violence to solve disputes and respond to perceived threats, with killers protected from prosecution regardless of whether the victim actually posed a danger.

In the case of both Zimmerman and Dunn, their perception of the "threat" posed by Trayvon Martin and Jordan Russell David, respectively, may have been motivated by the fact that their victims were black; as such, the ALEC/NRA legislation can put the decision to take a life in the hands of a person whose fears are motivated by racial bias or other irrational prejudice.

As CMD reported [3], NRA lobbyist Marion Hammer helped draft [5] the Florida Stand Your Ground law in 2005, and reportedly [6] "stared down legislators as they voted," then stood behind Governor Jeb Bush as he signed the bill into law. Just a few months later, Hammer presented the bill [7] to ALEC's Criminal Justice Task Force, and the NRA boasted [7] that "[h]er talk was well-received." The corporations and state legislators on the Task Force -- which was chaired by Wal-Mart [8], the nation's largest retailer of long guns -- voted unanimously to approve the bill as an ALEC model. Since becoming an ALEC model it has become law in dozens of other states, and the number of homicides classified as "justifiable" has dramatically increased [9].

Through ALEC, the NRA has also pushed a variety of bills [10] to expand access to and use of firearms, such as concealed carry legislation. Wisconsin Gov. Scott Walker signed versions of the concealed carry and "Stand Your Ground" bills into law in 2011, after which the NRA gave him an award [11] and spent $815,000 [12] on his 2012 recall election.

NRA Asserts: "The only thing that stops a bad guy with a gun is a good guy with a gun."

Evidence suggests Trayvon Martin and Jordan Russell David posed no threat to their killers, but even when a real "bad guy" does exist, humans are imperfect and have imprecise judgment, particularly in the chaos surrounding mass shootings. The massacre at Fort Hood, Texas, for example, was at a military base with people trained to use firearms and have fast response times, but that did not stop a single gunman from killing 13 and wounding 29.

And even the best-intentioned "good guys" often cannot determine who poses a genuine threat in a chaotic situation, which is one of the reasons why law enforcement overwhelmingly opposes [13] NRA-backed efforts to arm more civilians.

When Jared Loughner shot Congresswoman Gabrielle Giffords and 19 others (six of whom died) in Tucson, there was one "good guy" in the area, Joe Zamudio, who was carrying a concealed handgun. As he told Fox & Friends: "I came around the corner [and] I saw a man holding a gun. And that's who I at first thought was the shooter."

But when Zamudio arrived, Loughner had already been subdued by unarmed civilians when he paused to reload -- a powerful argument for banning high-capacity clips -- and the person holding the gun at the time was one of the heroic citizens who had wrestled it away from Loughner. And Zamudio almost shot him.

"I was very lucky. Honestly, it was a matter of seconds. Two, maybe three seconds between when I came through the doorway and when I was laying on top of the real shooter, holding him down. So, I mean, in that short amount of time I made a lot of really big decisions really fast. ... I was really lucky."

Not everyone in that situation would have Zamudio's good sense and judgment.

But an increasingly-armed society means more business for the gun manufacturers that fund the NRA -- and who cares if a person has good judgment, or is really a "good guy" at all, as long as they continue buying guns and buying into the NRA's fear-mongering.