John Paul Stevens made the call in an op-ed in The New York Times three days after the "March for our Lives" -- the biggest pro-gun control demonstration in the history of the US.

"Rarely in my lifetime have I seen the type of civic engagement schoolchildren and their supporters demonstrated in Washington and other major cities throughout the country this past Saturday," wrote the former high court judge, now aged 97.

Stephens, who was nominated to the Supreme Court by Republican president Gerald Ford in 1975, said the protests "reveal the broad public support for legislation to minimize the risk of mass killings of schoolchildren and others."

But he said activists, who are calling for a ban on assault rifles and raising the legal age to buy a firearm to 21, should go further in their demands.

"They should demand a repeal of the Second Amendment," he said.

The amendment states that "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."

"Today that concern is a relic of the 18th century," when states worried that a standing national army could be used against them, Stevens said.

In 2008, the Supreme Court held that the Second Amendment protects the right of individuals to possess firearms for self-defense in the home, in the landmark case "District of Columbia v. Heller," ruling a ban on handguns and laws on storage requirements for rifles and shotguns violated this.

A decade on, Stevens remains convinced that decision was "wrong and certainly was debatable" -- and that it has handed the powerful National Rifle Association "a propaganda weapon of immense power."