In its 4-4 ruling barring President Obama’s executive order on immigration from going into effect, the Supreme Court proved that Obama was right the first time: He lacked the power to change the law on his own.

As recently as December 2014, the president lectured supporters that the Constitution didn’t allow it: “The notion that I can just suspend deportations through executive order, that’s just not the case.”

Then, a few months later, after Congress again refused to pass the law he wanted, he decided to see if he could get away with it anyway — issuing an order that not only suspended deportation for millions, but also gave them the right to work legally.

Thing is, he was only one high-court vote away from succeeding, because the liberal justices were willing to ignore the Constitution — as Obama himself understood it just two years before — to support liberal policy.

Should Hillary Clinton win in November, she’ll get to fill the Antonin Scalia seat on the court, and likely two more seats soon thereafter. The Supreme Court will no longer stand in the way of the Democratic agenda, even when Democrats lack the votes in Congress.

And she’s already promised to out-do Obama on executive actions. On immigration, Clinton said she’d “go as far as I can, even beyond President Obama.”

It won’t stop with immigration. Clinton & Co. want executive action on gun control, labor-union power, “environmental protection” and pretty much their whole wish list.

And it’s not a two-way street: Conservative jurists aim to observe the letter of the law, not their ideology. That’s why GOP-appointed justices have slapped down Republican presidents from George W. Bush back to Nixon and Eisenhower, and why Chief Justice John Roberts saved ObamaCare.

It’s not just the White House at stake this Election Day. It’s the rule of law.