Retired Supreme Court Justice John Paul Stevens rattled the National Rifle Association’s cage — with predictable results. Stevens, impressed by March for Our Lives demonstrations last Saturday, called for repeal of the Second Amendment, which he said is antiquated.

The amendment, as you know, states “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.” It was adopted out of “concern that a national standing army might pose a threat to the security of the separate states,” Stevens wrote Tuesday in an op-ed in The New York Times. “Today that concern is a relic of the 18th century.”

Told ya so, the NRA crowed.

“I have long said the ultimate goal of the left is the complete repeal of the Second Amendment,” said NRATV host Grant Stinchfield. “This is proof, my friends.”

No, actually, it’s not.

Stevens was expressing his own provocative opinion. He doesn’t speak for “the left” any more than the NRA speaks for all gun owners, many of whom support common-sense gun safety measures.

The inspiring young protesters would be wise to thank Stevens, 97, for his support and get to work lobbying their legislators, registering to vote, backing candidates who support stricter gun laws and voting.

Repeal isn’t “simple,” as he said, or even doable. It’s a distraction, and a self-defeating one.

President Trump’s response to Stevens — complete with the laying on of the caps lock key and exclamation points — shows he thinks this is just the issue to fire up his base.

“THE SECOND AMENDMENT WILL NEVER BE REPEALED! As much as Democrats would like to see this happen and despite the words yesterday of former Supreme Court Justice Stevens, NO WAY. We need more Republicans in 2018 and must ALWAYS hold the Supreme Court!” Trump tweeted at 4:52 a.m. Wednesday.

Yes, 4:52 a.m.

Only about one in five voters strongly or somewhat favors repeal, according to an Economist-YouGov poll in February, which found tepid support for repeal among Democrats, about 39 percent. Only 8 percent of Republicans supported repeal.

Stevens, appointed to the court by Republican President Gerald Ford, became a liberal bulwark. He retired in 2010, two years after writing a dissent in District of Columbia v. Heller, which determined there is an individual right to bear arms. Stevens still believes the court’s decision in that case was wrong.

“In 1939 the Supreme Court unanimously held that Congress could prohibit the possession of a sawed-off shotgun because that weapon had no reasonable relation to the preservation or efficiency of a ‘well regulated militia,’” he wrote in The Times.

The idea that gun rights were limited held until the 1980s, when the NRA and other groups mobilized, he said.

Amending the Constitution is intentionally difficult. The likely path requires a two-thirds vote of both the House and the Senate and ratification by three-fourths of the states.

Alternatively, two-thirds of the states could call

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