The US Supreme Court on Thursday declared for the first time that the US Constitution protects an individual's right to carry a handgun in public for self-defence, handing a landmark victory to gun rights advocates in a nation deeply divided over how to address firearms violence.

The 6-3 ruling, with the court's conservative justices in the majority and liberal justices in dissent, struck down New York state's limits on carrying concealed handguns outside the home. The court found that the law, enacted in 1913, violated a person's right to "keep and bear arms" under the US Constitution's Second Amendment.

The ruling, authored by Justice Clarence Thomas, declared that the Constitution protects "an individual's right to carry a handgun for self-defence outside the home."

Thomas added: "We know of no other constitutional right that an individual may exercise only after demonstrating to government officers some special need."

The New York restriction is unconstitutional because it "prevents law-abiding citizens with ordinary self-defence needs from exercising their right to keep and bear arms," Thomas added.

The justices overturned a lower court ruling throwing out a challenge to the law by two gun owners and the New York affiliate of the National Rifle Association, an influential gun rights group closely aligned with Republicans.

The decision represents the court's most important statement on gun rights in more than a decade. The court in 2008 recognised for the first time an individual's right to keep guns at home for self-defense in a case from the District of Columbia, and in 2010 applied that right to the states.

The new ruling underscored how the 6-3 conservative majority on the court is sympathetic to an expansive reading of Second Amendment rights.

Under the New York law's "proper cause" requirement, applicants seeking an unrestricted concealed carry permits must convince a state firearms licensing officer of an actual, rather than speculative, need for self-defence. Officials could also grant licenses restricted to certain activities, such as hunting or target practice.

The ruling could lead to many more people securing the licenses to carry concealed handguns in the state, undermine similar restrictions in other states and imperil other types of state and local firearms restrictions nationwide by requiring judges to scrutinise them with a more skeptical eye under the Constitution. (Reuters)