That case "unleashed a torrent of litigation," said University of California, Los Angeles Law School professor Adam Winkler, a Second Amendment expert.
Much of it is either started by the NRA or supported by the organization, which offers financial assistance and legal help to people embroiled in lawsuits and legal trouble because they own guns.
Winkler said the latest legal battle over the Second Amendment centers on expanding the right to carry guns outside the home, which is why the NRA is representing Peruta and several other gun owners who are challenging restrictions blocking permission to carry concealed firearms in public.
Peruta filed a lawsuit in 2009 after the San Diego County sheriff rejected his application for a concealed-weapons permit because Peruta failed to show he had a "good cause" to carry a gun outside his home. Peruta owns a motocross track in Connecticut, but he and his wife spend many months each year in San Diego living in their recreational vehicle.
Peruta said he wanted permission to carry a gun weapon for protection, but the sheriff and California law said he needed a better reason, such as that his occupation exposes him to robbery.
"I'm not a hunter. I'm not a collector or a target shooter," Peruta said. "I'm not a gun crazy. But I do want to protect myself."
After a federal judge refused to toss out the lawsuit in 2010, the NRA took over the case for Peruta. "The NRA is the 800-pound gorilla in this fight," he said.
In February, the U.S. 9th Circuit Court of Appeals, citing the Supreme Court's 2008 ruling, struck down California's "good cause" requirement, ruling that self-defense was a good enough reason to issue a concealed-weapons permit.
The California attorney general and the Brady Campaign to Prevent Gun Violence are seeking to overturn that decision after San Diego County Sheriff William Gore said he would abide by the court decision.
"The issue is important: As a result of the decision, residents and visitors will be subjected to the increased risk posed by the carrying of loaded, hidden handguns on the streets of San Diego County by persons with no good cause to do so," a lawyer for the Brady organization wrote in a court filing seeking permission to formally oppose Peruta and the NRA in an appeal.
The 2012 shooting at Sandy Hook Elementary School in Connecticut —where a gunman used an assault rifle to kill 20 children and six others— led some and states to enact laws banning high-capacity magazines enacted by cities and states, and the NRA countered with lawsuits.
So far, federal judges across the country have unanimously rejected the NRA's legal challenges to these bans. Federal judges in recent weeks have upheld bans enacted by San Francisco and Sunnyvale, a Silicon Valley suburb about 40 miles to the south.
"California has always been sort of one of the front-line states," said Chuck Michel, a Long Beach lawyer who represents the NRA in many of its California-based cases. Michel said the NRA and other Second Amendment advocates have filed "a whole slew of lawsuits" using the 2008 high court ruling to challenge gun-control laws enacted after Sandy Hook.
NRA spokesman Andrew Arulanandam said the group has always involved itself in furthering gun rights in court, but that legal challenges have increased since 2008.
NRA has been involved in "hundreds of cases" and spends "tens of millions" of dollars out of its $300 million annual budget on legal issues, Arulanandam said.