I’m going to defend the U.S. Supreme Court’s decision on the constitutionality of the 2010 Affordable Care Act (the “ACA”), even before I know what the Court’s decision will be.

That’s because the ACA, derisively dubbed “Obamacare” by the GOP, represents the high-water mark of the federal government’s attempt to control economic decisions by its citizenry and by the states. Whether that attempt should pass constitutional muster is a close question, one about which reasonable judges can legitimately disagree.

Whichever way the Court’s majority votes, it’s certain that at least half the country will be hopping mad and accuse the prevailing justices of making a politically motivated decision.

But the Court doesn’t really make political decisions (though its decisions often have profound political consequences). Nor are its rulings based upon public opinion polls, constituent mail, the number of protestors picketing outside its doors, or media coverage. In other words, it doesn’t act like Congress or the President.

Its core job is to call “foul” whenever any branch of government, including the judiciary, fails to stay within the confines of its constitutional authority.

In order to perform this essential role, the Court has to construe the meaning of the Constitution. This task involves interpreting the words on the document, taking into consideration the history of its creation, the Court’s own previous (“precedential”) decisions interpreting it, and the changing political, social, economic and technological developments over the past two-plus centuries since ratification.

Unlike Congress, which is sharply divided along many partisan and ideological lines, the only real fault line on the Court is between conservative justices who believe their decisions should hue closely to the precise language of the Constitution and the framers’ original understanding of what they drafted, and the more liberal members who believe that that precedential decisions and changing societal conditions should be given substantial weight as well. The leading advocate of the first approach is the outspoken Justice Antonin Scalia.

The central constitutional question raised by the ACA is the so-called “individual mandate,” which requires most people to maintain a minimum level of health insurance coverage for themselves and their tax dependents beginning in 2014. They can do so by obtaining coverage through employer-sponsored insurance, individual insurance plans, including those to be offered through the new health insurance exchanges, a grandfathered health plan, government-sponsored coverage such as Medicare or Medicaid, or similar federally recognized coverage.

There’s been a substantial amount of federal legislation over the past 70 years regulating the economy, public health and safety, which the Supreme Court has justified under Article I, Section VIII of the Constitution, giving Congress the power to regulate interstate commerce. The Interstate Commerce Clause has allowed the Court to get around the roadblock of another important constitutional provision, the Tenth Amendment, which states, “Powers not delegated to the federal government are reserved to the states and the people.”

The Tenth Amendment means that individuals are usually free to make their own decisions, without government interference. However, when government does intervene to regulate for common good (exercising what has been traditionally known as the “police power”), such regulation should issue from state or local governments unless the Constitution expressly grants such power to the federal government.

Since the New Deal, the Interstate Commerce Clause has been elastically stretched to justify federal “police power” legislation regarding matters which really involve local commerce or no commerce at all.

Doubtless the framers would have been astonished by the extent of federal government’s reach today. For instance, in the early 1700s, a form of vaccination for smallpox, one of the worst epidemic scourges of the era, was successfully tried in Boston, and, during the Revolutionary War, Gen. George Washington ordered the inoculation of all Continental Army troops and recruits who had not already contracted the disease.

Yet the Constitutional Convention, which Washington chaired, gave no power to the federal government to order mandatory smallpox inoculations. Nonetheless, today the federal Food and Drug Administration approves and regulates the sale of numerous food, pharmaceutical, cosmetic and other products in order to protect public health.

Not surprisingly, during oral argument late last month, the more conservative members of the Court wanted to know whether the ACA exceeded Congress’s right to legislate about “police power” matters, and, if it didn’t, just how much further Congress could go without crossing the line.

Thus, Justice Scalia’s much maligned question to the Solicitor General was less flippant than it sounded, “Everybody has to buy food sooner or later,” Justice Scalia said, drawing a comparison between groceries and health insurance. “Therefore, everybody is in the market; therefore you can make people buy broccoli?”

In other words, if the government can force people to buy insurance, thus compelling them to participate in interstate commerce and be regulated under the Interstate Commerce Clause, is there any “police power” measure that the Tenth Amendment forbids the federal government from requiring of its citizens?

The Constitution’s drafters were concerned, above all, with achieving balance — with preventing the extremes of over-centralization of power, overly decentralized power or mob rule, any of which, they realized, could doom the fragile new republic. At various times in our history, the balance has seemed to tip in one direction or the other, and the Supreme Court has been called upon to right the balance. This may be one of those times.

It’s hard to know whether, as public policy, the ACA will live up to its promise to make health care affordable for all Americans (without bankrupting the Treasury or destroying the quality of health care in the process). I don’t have a clue, and I expect even the experts responsible for drafting the legislation can’t predict the outcome.

That’s because the legislation itself – a whopping 955 pages long, approximately 100 times as long as the Constitution itself — seeks to bring about such far-reaching and complex changes to an already highly intricate health-care system. How those changes will play out in reality, against the backdrop of kaleidoscopic technological innovations and economic, political and personal choices, is anyone’s guess.

But the Supreme Court doesn’t have to worry about whether the health-care law will achieve its stated goal. It simply has to decide whether the legislative mechanism selected to achieve that goal is constitutional.

Whichever way that decision comes down, it will be a victory for the rule of law under the Constitution.