SAN FRANCISCO — Millions more Americans will have the right to drive and walk around U.S. cities with hidden, loaded guns if former police officer and videographer Edward Peruta wins his fight to carry one on assignment.

The sheriff in San Diego rejected Peruta’s application for a permit to carry his Colt 1911 .45 caliber pistol while traveling with cash and expensive equipment in high-crime California neighborhoods. Peruta sued, and a three-judge panel of a federal appeals court ruled in February that the Second Amendment entitles any responsible, law-abiding citizen to possess a concealed firearm in public for self defense.

If the ruling stands after further review by the full court, it may put the scope of the right to bear arms back in front of the Supreme Court, six years after the justices struck down a Washington, D.C., law that banned handguns in the home.

Since that landmark decision, state and local government efforts to regulate gun possession have largely survived legal attack by gun-rights advocates. A victory for Peruta at the high court could reverse that trend and be used to attack strict public-carry laws in New York City, Boston, Baltimore and Washington. That would expand the number of people with concealed guns on city streets to as much as 5 percent, according to Adam Winkler, a law professor at the University of California at Los Angeles.

“It would mean that the discretionary permitting process in many major cities would be invalidated,” Winkler said. “You’re absolutely talking about millions more people having permits to carry guns.”

The Supreme Court has rarely waded into Second Amendment disputes, the 2008 case being the first in 70 years. In that ruling, the court in a 5-4 vote said for the first time that the Constitution protects individual gun rights, even if a person isn’t affiliated with a state-run militia. In a 2010 decision that expanded on that one, the court ruled 5-4 that states and cities are bound by the Second Amendment, as well as the federal government. Both cases involved handgun possession in the home, not in public.

Chuck Michel, Peruta’s lawyer and West Coast counsel for the National Rifle Association, said it was his idea to flag Peruta’s 2009 lawsuit to the NRA as worthy of the organization’s institutional support because of its potential to reach the Supreme Court.

Peruta lives and works in Connecticut as an investigator for an attorney who handles firearm-related civil and criminal cases. On YouTube videos, he describes himself as an NRA instructor and the director of Connecticut Carry, a group dedicated to educating citizens, lawmakers and law enforcement officials about gun rights. Peruta declined through Michel to comment on the case.

To the NRA, which is supporting Peruta’s case, more people packing pistols, revolvers and other sidearms may mean the difference between life and death. With 1.9 million of California’s 38 million residents armed, criminals would be deterred in the most populous state because they wouldn’t know who’s carrying a gun, said Chuck Michel, Peruta’s lawyer and the NRA’s West Coast counsel.

“No one is going duck hunting when 5 percent of the ducks might shoot back,” he said in an interview.

Gun control advocates say that math is dangerous, because without stringent permitting, the odds go up that guns will fall into the wrong hands.

“The more guns you have in public spaces, the more likely you are to have altercations between people that become deadly,” Mike McLively, a lawyer at the Law Center to Prevent Gun Violence, said in an interview.

Last year, the U.S. murder rate dipped to a historic low last year while the number of concealed weapons permits nationwide soared to an all-time high.

There are now more than 11 million permit holders in the U.S., and the growth has accelerated with almost 1.5 million new permits issued in the past year, according to a July report by the Crime Prevention Research Center.

McLively credits the surge in permits to a concerted gun lobby push at statehouses nationwide to radically weaken restrictions on concealed weapons over the past 30 years. In 1981, 19 states prohibited the carrying of concealed weapons. Now, all states allow the practice with varying degrees of regulation.