Among the several comments I have received about health care reform is the suggestion mandates to buy health insurance are unconstitutional. I hadn't hear any debate about this, but I have been pretty well out of the loop (no, still not done).
My initial reaction is why health insurance would be any more unconstitutional than auto insurance, but luckily better minds than mine have pondered this question.
Before we get started down this road, yes, the individual mandate is constitutional. For a roundup of the argument, see this Tim Noah piece. For a longer, more technical explanation, see this post by law professor Erik Hall.
The summary is that you can look at the individual mandate as a tax, which is constitutional, or as a regulation forcing private actors to engage in a certain transaction, much like the minimum wage, which is also constitutional. I've also heard scholars mention auto insurance, which is an obvious analogue, and the Americans With Disabilities Act, which proved that the government can order businesses to install ramps, despite the fact that the constitution doesn't explicitly give the federal government jurisdiction over entryways. [More]
And of course, the mind wanders to the ethanol mandate...