Four issues have dogged ObamaCare from the moment it was signed into law in 2010.

First was its constitutionality. That was resolved in its favor by the Supreme Court last June, but at a huge cost: In that decision, the federal government lost its ability to penalize states that refused to set up ObamaCare “exchanges,” which (for complicated reasons) will put the new system’s overall funding mechanism in some peril.

Second is its philosophical basis. ObamaCare is a national health-care system that essentially puts one-sixth of the US economy under government control. Now, there are many people for whom this is not a problem; indeed, lots of them would’ve preferred the wholesale nationalization of American health care by imposing a so-called “single-payer system.”

But for those committed to the principles of limited government — and who believe the current system is already overly distorted by governmental interference — ObamaCare is a calamity at its very root. This conviction explains why conservatives haven’t simply given up and accepted the inevitability of ObamaCare; to do so would be to surrender the very core of American conservatism itself.

Third is its feasibility. Can this immensely complex new system actually be put into place without throwing American health care into a state of chaos that would make its present complexity look as perfectly organized as an alphabetized bookcase?

Fourth, and most important, is its effectiveness. The promise of ObamaCare is that it will deliver better health care in a more rational way at a more reasonable cost than the current system. If it doesn’t do that — if we end up with health care no better and possibly worse, delivered in a less rational fashion that is more expensive — then it will be (at the least) $1 trillion and (at the worst) $2 trillion spent to make things worse.

An unexpected real-world test of the potential effects of ObamaCare has been taking place in Oregon over the past four years. That state’s Medicaid program was expanded in a way that has made it possible to measure the difference between people in an ObamaCare-like system and people not in such a system.

And the results? In the words of the Washington Examiner’s Philip Klein, the best daily journalist writing on health care, “Researchers found that those who enrolled in Medicaid spent a lot more on medical care than those who weren’t able to enroll, but didn’t significantly improve their health outcomes.”

Among those researchers: Jonathan Gruber, an MIT economist who played a leading role in the design of both RomneyCare in Massachusetts and ObamaCare.

Gruber and his colleagues found that “coverage generated no significant improvements in measured health outcomes in the first two years, but it did increase use of health services, raise rates of diabetes detection and management, lower rates of depression and reduce financial strain.”

In other words, it wasn’t a complete waste, given the diabetes detection and reduction of depression. And it was a study only of 17 months; over a longer period of time, we might find that the government-care users have used preventative care in such a way that they are better off than the others.

For these reasons, some ObamaCare cheerleaders are acting as though the results are fine. That’s nice for them, but no politician who has to stand up for the most controversial and far-reaching legislation in generations will be willing to advance an argument that it’s fine for ObamaCare to cost considerably more per patient — at an overall pricetag in the trillions — with no significant improvement per patient.

That is why Ezekiel Emanuel, one of the most honorable liberal health-care experts and an ObamaCare partisan and designer, acknowledged on Wednesday that the results were “disappointing.”

And it’s why, aside from the constitutional issue, the controversies dogging ObamaCare are far from over.

It’s not just that it might not work well; it’s that the philosophical argument against ObamaCare has always been based on the proposition that a government-run system can’t work well.

If things go the Oregon way, ObamaCare supporters aren’t going to have a viable argument in its favor — and its repeal and replacement will begin to look less like a conservative chimera and more like the practical and sensible thing to do.