The conservative-majority US Supreme Court is to hear a gun rights case on Wednesday that could lead to looser restrictions on carrying firearms in public.

At issue is a challenge backed by the gun lobby to a New York law that regulates the carrying of guns outside the home.

It will be the first major case involving the Second Amendment constitutional right to bear arms heard by the nation's highest court in more than a decade.

The high-stakes case will be argued before a Supreme Court with a 6-3 conservative majority following the nomination of three justices by former president Donald Trump.

The court had previously declined to take up several Second Amendment cases, but it underwent a shift to the right under Trump and the three justices he named have been historically sympathetic to the arguments of gun owners.

This has raised fears among gun control advocates that local restrictions such as the New York law could be in jeopardy.

In a landmark 2008 case, the Supreme Court ruled the Second Amendment ensured a right to gun ownership, but left it up to cities and states to set their own rules on carrying weapons outside the home.

This has led to a patchwork of regulations across the country.

Eric Tirschwell, executive director of Everytown Law, the legal arm of gun control group Everytown for Gun Safety, said the stakes in the case are "incredibly high."

"The fact the court even took up the case should give all of us cause for concern," Tirschwell said.

"The gun law at the heart of this case has been on the books for over a hundred years, and it's grounded in a centuries-long tradition of regulating the carrying of firearms in public," he said.

'Proper cause'

The more than century-old New York law currently requires someone applying for a permit to carry a gun outside the home to establish "proper cause."

The suit to be heard by the Supreme Court was brought by two men who were denied permits to carry handguns for self-defense.

Their appeals were rejected by lower courts and the Supreme Court agreed to hear the case.

The court said it would limit arguments to the question: "Whether the state's denial of petitioners' applications for concealed-carry licenses for self-defense violated the Second Amendment."

The Second Amendment to the Constitution is subject to various interpretations.

It reads: "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."

For the National Rifle Association and many gun owners, it guarantees the rights of citizens to carry weapons.

Eric Ruben, an assistant professor at the SMU Dedman School of Law and a Brennan Center fellow, said that if the Supreme Court strikes down the New York law "it will mean that the government is limited in the way that it can restrict the carrying of guns in public."

"As it stands today, the states where liberal politicians hold power are more likely to restrict the carrying of guns in public," Ruben said.

"Removing barriers to carrying concealed handguns in public places has been a primary goal of the gun rights movement, of the National Rifle Association, and of many conservative politicians."

Joseph Blocher, a law professor at Duke University, said about 80 million Americans currently live in states restricting the carrying of firearms in public.

"If the Supreme Court strikes down New York's 'proper cause' law, it could immediately call into question the constitutionality of similar laws in other states like California, New Jersey and Massachusetts," he said.

There were more than 43,000 gun-related deaths in the United States last year, including suicides, according to the Gun Violence Archive.

The Supreme Court has until June 2022 to issue a ruling in the case.