Although he sided with liberal members of the Supreme Court, Chief Justice John Roberts struck what could be a home run for conservatives.

Or not.

In this month’s decision that the Affordable Care Act was something Congress had the power to pass, the justices considered two parts of the Constitution.

One was the power to impose taxes. This is a clear power. And it was employed by Roberts and the four liberal justices.

There has been a great hue and cry about how President Barack Obama and his friends in Congress explained time and again that the act’s requirement that everyone buy (or be provided) health insurance was not a tax.

Roberts said it walked like a duck, quacked like a duck …

End of story.

The other basis is in Article I, Section 8. “To regulate commerce with foreign nations, and among the several states, and with the Indian tribes” is what it says and, in short, it’s called the commerce clause. The four liberal justices preferred using the commerce clause, but Roberts wouldn’t go along. And, of course, they had to have five yeas.

For decades, the commerce clause gathered dust. Then cars came along, and bus lines and truckers. States got into all kinds of scrapes with each other, ranging from where highways would meet up at state lines to excise fees on buses and trucks passing through. “Wait,” Congress said, “we have the power to regulate commerce. Highways and buses and trucks are used for commerce. We’ll pass laws to deal with these conflicts.”

And the commerce clause got a little muscle.

In the 1960s, TV news brought the evils of segregation to dinner tables across America. “Make it stop,” the people said. Congress, however, was at a loss. Jim Crow laws were state enactments. Congress couldn’t just invalidate them.

But wait a minute. Buses are interstate transportation. “Let’s use the commerce clause as the basis for making segregation against federal law,” Congress said. “Further, since the food served in restaurants crosses state lines, let’s make segregation of dining places illegal.”

They did, and the laws were upheld by the nine justices serving at the time.

Since then, the majority of consolidation of power away from the state legislatures and into the purview of the federal legislature has been enacted under the authority of the commerce clause.

This has included the “enticements” that have become so common. Congress wanted the minimum age to buy whiskey or beer or firearms to be 21 nationwide. Congress “told” states to change their state laws — or face loss of funding. Congress wanted a minimum age to license drivers. Congress told states to comply or have federal highway funds withheld.

Roberts and the four conservative justices appear to have limited this tactic, calling it “coercion.” What they may be saying — may be — is that Congress may no longer use the commerce clause this way.

A few are very alarmed that this might result in a rollback on civil rights legislation. That’s not likely.

The rest remains to be seen.

The “enticement” in the Affordable Care Act struck down was that federal support of existing state Medicaid programs would be halted if states refused to expand the eligibility threshold to 133 percent of the official poverty level ($31,000 for a family of four).

Texas and seven other states say they will not expand their rolls and Roberts and four other justices say there’s nothing Congress can do about it. The Constitution, a majority ruled, doesn’t allow that anymore.

Mississippi Gov. Phil Bryant has been making noises about not expanding, but Mississippi likely will.

To do otherwise would be to say no to billions flowing into the state — and no to the clinics, hospitals and pharmacies that would be on the receiving end of those billions.

While Bryant and others correctly fear what “Obamacare” will do to the state budget, Mississippians, like all Americans, inexplicably believe any funds from the federal treasury are “free.” To stand on principle that Congress is over-reaching is one thing. To turn down “free money” is quite another.

Overall, it shouldn’t pass without notice that the Supreme Court has slapped the hands of Congress. Yes, a tremendous tax has been upheld, but the power of federal lawmakers to bully states has been sharply curtailed.

And that’s the law, least until there’s a personnel change in the rank and file of those whose job is to tell us what the Constitution means on any given day.