The Supreme Court decided the individual mandate in Obamacare, that everyone must have medical insurance by 2014, is constitutional. Presumably the constitutional clause that allows this is Section 8 - Powers of Congress, where one sentence is: To regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes;
So obviously the contentious work is "regulate." It can be taken many ways, and obviously the Supreme Court has decided to take it as "the Federal government can force citizens to purchase products from private corporations." Quite the precedent! I wonder when we'll be forced to purchase cars from GM?
Do you know why the health care issue has become so contentious? Because the government got involved a long time ago and started committing public funds to it. As soon as people are forced into transactions (through taxation, at the very least) you get fierce divisions among the people. Statists' solution to the problems created by the state is more state intervention. Ideologically, statists can't see that going towards less intervention and more freedom will reduce the problems, not exacerbate them.
And don't tell me that Obamacare must be good because healthcare companies favor it. Of course they do! This is guaranteed revenue! Well, don't expect the economy to recover anytime soon.