As much as I consider Obamacare disastrous for the future of health care in the United States, I am even more concerned about the grasping power of the federal government.

If the Patient Protection and Affordable Care Act were declared constitutional by the U.S. Supreme Court—which yesterday announced that it will hear the case—it  would be an unprecedented expansion of federal authority.

One of the key issues is whether the federal government can require citizens to purchase a product–health insurance–and impose penalties for failure to do so.

David B. Rivkin and Lee A. Casey, former George H. W. Bush Justice Department lawyers who represented the 26 states in the lawsuit that will be heard by the Supreme Court, succinctly tell us what is at stake:

 If Congress can require individuals to buy or otherwise obtain and maintain health insurance simply because they may be said to impact commerce by their very existence, without regard to any particular activity in which they have chosen to engage, then there is no limit on federal power.

If Congress can require you to buy health insurance now, Casey and Rivlin argue, sometime in the future they could order you to buy (or sell) some other product that is deemed to have some economic impact on the country.

As awful as many of the other provision of Obamacare are, I will breathe a sigh of relief if this one aspect is struck down. The Court will consider whether this provision is severable—i.e., does the rest of the law stand if it is struck down.

An editorial in today’s Wall Street Journal notes:

The Obama Administration's answer to the law's multiple discrepancies, contradictions and nuances has been to go all-in on the argument that overturning the mandate will overturn the entire law. It's true that without the mandate the law is unlikely to work, but the law is such a Rube Goldberg contraption that it won't work with the mandate.

We'd like to see the entire law overturned, but the mandate deserves its own constitutional judgment. It shouldn't be found constitutional merely because Justice's lawyers say its excision would ruin the entire law. Congress can't drop unconstitutional provisions into laws hoping that the Court will bless them simply because not doing so would invalidate the larger law.

Rivlin and Casey think it is “highly unlikely” that the Supreme Court will “junk nearly 200 years of its own jurisprudence” by ruling that it is constitutional to force citizens to buy a product. But they seem less sure on other aspects of the case.

It is almost impossible to overstate the significance of the Supreme’s Court’s ruling in this case.