On Thanksgiving eve, the Obama administration dumped reams of mind-numbing ObamaCare regulations into the Federal Register — including yet more unilateral rewrites of the Affordable Care Act.

Dropping the rules as most Americans were busy preparing for the holiday made a mockery (again) of President Obama’s promise to have “the most transparent administration in history.” The stunt has even worked to keep most of the media from reporting on the rules.

Yet the changes these regulations make in the health care law are substantial.

For one, the president is redefining what health plans are “adequate” for larger employers (100-plus workers) to offer under the Affordable Care Act. He’s also “asking” insurers to pay for new benefits — while warning that, if they don’t, they may be forced to.

Under the Constitution, Obama lacks any authority to make such changes to the health law, or any law. Only Congress has that power. But he’s doing it, and not for the first time.

The president has made two dozen changes to his health law by executive fiat, from delaying the employer mandate to allowing people to keep health plans that don’t meet ObamaCare standards.

In fact, the House of Representatives is suing him (after Obama explicitly challenged it to do so) for making changes without Congress’ OK.

Of course, the president says he’s merely “taking executive actions to help people.”

Yet, as a former constitutional law professor, he surely knows better. And his mother surely warned him about the perils of “the end justifies the means” reasoning — even when the end is helping people.

In any case, last week’s changes, like the president’s previous fixes, create new losers as well as winners — the sort of tradeoffs that legislators are supposed to weigh in our system of government. The basics:

Obama will require large employers to provide more coverage than the Affordable Care Act specifies. The move disqualifies plans now offered by 1,600 employers to 3 million workers, according to Kaiser Health News. Those employers will have to find a way to cover the higher costs — and some will surely do so by stopping coverage for spouses or part-time workers.

The new rules suddenly treat state high-risk pools as adequate coverage under the Affordable Care Act — a 180 from what the law actually says.

When the ACA became law, these plans for people with chronic illnesses were offered in 35 states. Winners will be those who live in the 10 states that haven’t yet phased out their high-risk plans. Losers: the many thousands in 25 states that already gave up their plans to comply with the ACA’s mandates.

When the ACA became law, these plans for people with chronic illnesses were offered in 35 states. Winners will be those who live in the 10 states that haven’t yet phased out their high-risk plans. Losers: the many thousands in 25 states that already gave up their plans to comply with the ACA’s mandates. The rules tell insurers to give new enrollees a 30-day grace period during which they can continue to use doctors not in their plan’s network. Winners: people who need time to switch to in-network doctors. Losers: taxpayers — who’ll be obliged to bail out the insurers clobbered with the extra cost.

Speaking of bailouts, Section 1342 of the law promises taxpayer-funded bailouts to insurers that lose money selling plans on ObamaCare exchanges. But the bailouts can’t happen unless Congress appropriates the money, something the GOP-controlled Congress won’t want to do. Yet the new Federal Register notices explicitly double down on the administration’s pledge to make insurers whole if losses are bigger than expected.

By repeatedly contradicting the letter of the Affordable Care Act, these new rules add to a pattern of lawlessness in implementing the health law — even as the administration’s boldest misreading of the law is before the Supreme Court.

Two years after the justices ruled 5-4 to uphold ObamaCare’s individual mandate, the health law is back in front of the high court.

The issue this time, in King v. Burwell, is whether Obama is violating the law by handing out taxpayer-funded subsidies to ObamaCare enrollees in all 50 states. The letter of the law clearly allows subsidies only in the 14 states that established their own exchanges.

If the Supreme Court rules against the administration, enrollees would have to pay the actual cost of ObamaCare premiums — which would mean staggering hikes of 400 percent in many cases.

That could be the end of the president’s health law — or at least force him to actually negotiate with Congress on a complete rewrite tantamount to the Republicans’ “Repeal and replace” refrain.

Will the justices endorse the president’s rewriting of the law on ObamaCare subsidies? If so, they’ll surely be facing even more cases down the line, over all his other unilateral changes to his signature statute.