That answer isn't quite as obvious. In fact, there are reasonable arguments, such as one that Republican senator Orrin Hatch made in the Wall Street Journal over the weekend, that such a law would violate the U.S. Constitution.
Hatch's argument, written in an opinion article co-authored with conservative scholars Ken Blackwell and Kenneth Klukowski, is this:
It is one thing, however, for Congress to regulate economic activity in which individuals choose to engage; it is another to require that individuals engage in such activity. That is not a difference in degree, but instead a difference in kind. It is a line that Congress has never crossed and the courts have never sanctioned…Translated: If Americans voluntarily choose to purchase health insurance, the Feds can reasonably police insurers for fraud, for antitrust abuses, for labor law violations, and so on.
Some have argued that Congress may pass any legislation that it believes will serve the "general welfare." Those words appear in Article I of the Constitution, but they do not create a free-floating power for Congress simply to go forth and legislate well. Rather, the general welfare clause identifies the purpose for which Congress may spend money. The individual mandate tells Americans how they must spend the money Congress has not taken from them and has nothing to do with congressional spending.
But the authority to regulate interstate commerce doesn't necessarily imply the power to force people to engage in it or pay a penalty -- just as the power to regulate automobile safety standards doesn't imply the power to coerce Americans into buying Buicks. (Automobile insurance isn't a good parallel for two reasons: first, it's regulated by states, and second, if you don't have a driver's license, you don't need to buy insurance.)
At least that was the major argument last year, which I analyzed in a Taking Liberties article in September. It concluded: "Not even conservative and libertarian scholars who would like to see mandatory health insurance shot down by the courts are betting it will be, although Georgetown's Randy Barnett holds out some hope. Call it the difference between political preference and reality, or the difference between what is and what might be."
But that was before Sen. Ben Nelson, the Nebraska Democrat, cut his rather unusual deal to expand Medicaid in his state at the expense of taxpayers everywhere else -- a move that has been met with scorn on the part of his constituents and spurred the good senator to defend himself and his motives with a new television ad.
That has opened a new line of attack for critics of the Democratic plan.
Hatch argues that the Democratic proposal approved by the U.S. Senate is unconstitutional because it exempts some states from rules that apply to others, meaning Congress is no longer acting on behalf of the "general welfare" of all taxpayers. Hatch's other argument: the bill is unconstitutional because it forces states to establish specific kinds of health care bureaucracies and regulations. (Here's CBS News' preview of what happens next in Congress.)
Because the U.S. Constitution created a federal government with limited powers, and because it reserved all other powers to the states and the people, only laws grounded in the constitutional text are supposed to pass muster. In practice, though, courts have taken an expansive view of Congress' power to regulate as interstate commerce actions that take place in your own home -- even growing medical marijuana for your own use -- as well as Congress' ability to encourage and discourage behavior through its ability to tax and spend.
Questions about the constitutionality of a law don't arise very often, in part because judges are hesitant to strike down acts of Congress, and I suspect in part because politicians of both major parties tend not to stress limits that the law imposes on their own power and authority.
Not this time. Thirteen Republican attorneys general are planning a lawsuit unless Nebraska's special deal vanishes from the final legislation. William Mayton, a law professor at Emory University, says a recent Supreme Court opinion provides "grounds" for a legal challenge. A treat-everyone-equally grassroots revolt is afoot in some state capitols as well.
You can be pretty sure that, if there is a final health care bill sent to the president, there will be a flurry of lawsuits. And you can be pretty sure that you'll start to hear more about Supreme Court cases like Printz v. United States (1997), in which the majority opinion reiterated that "the federal government may not compel the states to enact or administer a federal regulatory program." That's why the Real ID Act has been a problem for the Feds -- they can inconvenience residents of non-compliant states, and they can offer cash payments to encourage compliance, but they can't order it directly.
Similarly, in Northwest Austin v. Holder, decided last June, the justices ruled that a law unreasonably "differentiates between the states, despite our historic tradition that all the States enjoy 'equal sovereignty.' … A departure from the fundamental principle of equal sovereignty requires a showing that a statute's disparate geographic coverage is sufficiently related to the problem that it targets."
And securing Ben Nelson's vote may not count as a sufficient, ah, problem in need of targeting.
Declan McCullagh is a senior correspondent for CBSNews.com. He can be reached at email@example.com and can be followed on Twitter as declanm. You can bookmark Declan's Taking Liberties site here, or subscribe to the RSS feed. Before becoming a CBS employee, Declan was the chief political correspondent for CNET, a reporter for Time, and Washington bureau chief for Wired.