The San Diego County sheriff denied Edward Peruta a permit to carry a concealed weapon. Christopher Haga’s gun collection was seized, and he was charged with crimes after he was mistakenly linked to a theft of assault weapons from a Fresno-area military base.

The National Rifle Association then lent legal assistance to both men as part of its aggressive legal and political campaign to blunt gun controls across the nation.

Emboldened by a seminal U.S. Supreme Court ruling in 2008 that upstanding Americans have the fundamental right to keep guns in their homes, the NRA has involved itself in hundreds of legal cases, many in California.

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 cities and states to enact laws banning high-capacity magazines, 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.

Among the cases is a lawsuit to repeal a Connecticut law that went into effect Monday, requiring a state license to buy rifles. Another is a challenge to New Jersey’s concealed-weapons law, which is similar to California’s.

Earlier this year, the U.S. Supreme Court refused to hear two NRA-backed cases. One sought to overturn a federal law barring licensed gun dealers from selling handguns to anyone under 21; the other was a Texas law barring people under 21 from carrying concealed weapons.

The NRA employs about two dozen in-house lawyers and hires many more outside lawyers — including former U.S. Solicitor General Paul Clement — to do battle in courtrooms across the country. It not only takes on weighty constitutional issues seeking to broaden the reach of the Second Amendment but also helps people who find themselves in trouble with the law because they own guns.

The NRA provided financial assistance and legal counsel to Christopher Haga, a gun collector who owns an auto shop in the Central Valley town of Parlier.

In 2011, Haga allowed federal firearms agents to search his house after they were tipped he had some of the 26 AK-74 assault rifles recently stolen from Fort Irwin, Calif. Haga’s lawyer Mark Coleman said his client had no connection to the theft and consented to the search after agents assured him they only were interested in stolen guns. After finding none, the investigators left — but they told Fresno police Haga had types of assault rifles prohibited by California law.

Following that tip, Fresno police searched Haga’s home and business and seized his gun collection. He was later charged with 35 felony gun counts.

With legal support and money from the NRA, Coleman challenged the legality of the guns search, and a judge sided with him. The district attorney dropped all charges late last year and returned Haga’s guns. Haga agreed to remove two of his AK-74s and a submachine gun from California.

The case was more about search-and-seizure laws than expanding gun rights, Coleman said. “But the NRA’s help was still valuable,” he said.