Today the Supreme Court will hear arguments on the individual mandate. At issue is whether Congress has the power under Article 1 of the Constitution to compel individuals to purchase the specified type of health-care insurance or face a fine.

The administration has several arguments: 1) Congress has the authority under its taxing power; 2) Congress has the authority under the Commerce Clause; or 3) Congress has the authority under the Necessary and Proper Clause.

The least likely to succeed is the taxing argument. The argument is not identical to Monday’s argument as to whether the Anti-Injunction Act (AIA) applies to bar consideration until the “tax,” that is the penalty for not obtaining health insurance kicks in. The AIA concerns a statutory issue; the taxing power goes to the meaning and intent of the constitutional taxing power. Nevertheless, this issue will get the least amount of attention and carries the least amount of weight.

In the brief of Paul D. Clement, counsel for the states challenging Obamacare, this argument comes at page 51 of an 82-page brief. He labels the argument faulty because “the States are challenging the mandate, not the penalty.” He argues that the Congress explicitly wanted to avoid a “tax” (perhaps because the president promised not to tax those making less than $250,000) and now cannot re-characterize the penalty for failure to comply with the mandate as a tax. This was not, Clement argues, some “linguistic oversight,” but was a deliberate legislative choice that the administration is now stuck with. In all likelihood, that argument will carry the day.

But the meat of the case is whether the Commerce Clause allows Congress to compel the purchase of a product. The 11th Circuit’s majority opinion found, “Few powers, if any, could be more attractive to Congress than compelling the purchase of certain products.” And, moreover, the appellate court could find no limiting principle that would prevent Congress from compelling purchase of any good or service. In essence the idea that health insurance is “unique” is not factually accurate from an economic perspective (mortgages, homes and other key purchases are greatly affected by others’ buying or not buying the same product) and more importantly, from a legal perspective. The argument that “Congress can’t or won’t do it again” is simply of no constitutional significance.

Clement argues in his brief that the extraordinary power to compel citizens to buy what they don’t want (as opposed to “regulate” commerce once it exists) was not exercised for 220 years. In essence, he argues that if the Supreme Court finds this power then the entire framework of a federal government with limited powers is decimated.

In the brief of the National Federation of Independent Business the attorneys make the point that the essence of the individual mandate is to compel enough individuals to take action to purchase insurance so that the insurance companies and its other customers can spread the cost, that is charge less. In such terms, it is quite stunning to consider, in counsels’ words, the “extent of the threat to individual liberty that occurs when Congress exceeds its limited and enumerated powers.”

There is still room for the Supreme Court to rule more narrowly on this case or more broadly in displacing existing Commerce Clause jurisprudence. If Chief Justice John Roberts is looking for a modest role for the courts, the decision may characterize this case as entirely unique, leaving other 10th Amendment case law untouched.

The final argument is the government’s last refuge. The Obama administration argues that if the Supreme Court can’t find authority in the taxing power or in the Commerce Clause, there’s always the “Necessary and Proper Clause.” The States and other parties will argue that this isn’t how the Constitution works. If Congress can get around the enumerated powers simply by gesturing toward the Necessary and Proper provision, then enumerated powers have no real limiting effect.

Todd Gaziano of the Heritage Foundation suggests we be on the lookout for several hints about where the justices are heading. Among these are the following:

The more the Court gets into the policy weeds, the better the government’s chances of success, due to the Court’s traditional deference to the political branches over matters of policy. In constitutional terms, this should be a simple case; making it complicated is to the government’s advantage. . . .

[And] what about Raich? Raich was the Court’s 2005 decision holding that, in furtherance of its goal of stamping out interstate commerce in marijuana, Congress could criminalize the possession of small amounts of marijuana within a state. The government claims that Raich allows it to reach nearly any conduct, or even no conduct, if its intention is to regulate an interstate market, but Justice Scalia’s Raich concurrence, which has come to overshadow the majority opinion’s shaky reasoning, offers a narrower view that defines more precisely the relationship between the Commerce Clause and the Necessary and Proper Clause. The justices’ questioning should shed light on what they think Raich meant and how it applies in this instance. In particular, watch for questions on whether the mandate is “proper.” Analogies to the rule against Congress “commandeering” the states or state officials will spell doom for the government’s position. Chief Justice Roberts, Kennedy, and Scalia are key.

But ultimately we return to the central issue: Does Congress have essentially unlimited powers? The 11th Circuit Court decided, “The federal government’s assertion of power, under the Commerce Clause, to issue an economic mandate for Americans to purchase insurance from a private company for the entire duration of their lives is unprecedented, lacks cognizable limits, and imperils our federalist structure.” If there are five justices who agree the mandate will fall, and the critical argument (to be heard tomorrow, along with the legality of the Medicaid provisions) will turn on whether the rest of the law can survive.

The importance of the case goes beyond one election and beyond healthcare. Conservatives make a compelling case that if it upholds ObamaCare, the Supreme Court will open a Pandora’s box, allowing new and previously unimaginable infringements on individual liberty and decimating the federal structure of our government. Listen carefully to Chief Justice Roberts (who, as Gaziano says, “has a reputation, though exaggerated, for avoiding controversial decisions and attempting to foster consensus on the Court where it may not easily lie”) and Justice Anthony Kennedy. In their hands may be power to enforce some limitation, any limitation, on the federal government.