Preventing someone from buying something is much different from compelling someone to buy something. You are comparing apples and oranges.
A law that prohibits someone from buying a bullet proof vest is much different from a law that forces every adult in a state to buy a bullet proof vest. In the former, you can argue that someone wishing to buy a vest is attempting to engage in commerce and thus subject to federal regulation. In the latter, a person not wishing to buy a vest has not engaged in commerce until Congress forces him to do so. In other words, in the latter case congress forced the commerce to occur in order to regulate that commerce.
The Obama administration has stated repeatedly that its mandate to purchase health insurance is not a tax. Congress is not imposing higher taxes on someone who does not buy health insurance.
-- Edited by Razorsharp on Tuesday 11th of January 2011 03:01:48 PM
Yesterday the Supreme Court refused to hear a court case on whether Congress overstepped in making it a crime for a felon to own a bullet-proof vest. Opponents of the law argued it violated the Commerce Clause of the Constitution.
Recall that the cases about the health care bill's individual mandate turn on the same issue: opponents claim that the individual mandate is unconstitutional, because the Commerce Clause does not license Congress to pass a law requiring that people buy insurance or pay higher taxes.
The Supreme Court will do what it wants, but it's hard to come up with an argument that it's OK for Congress to prohibit a bank robber from buying body armor, but not OK for Congress to impose higher taxes on people who don't buy health insurance.