Jason Mazzone argues in the New York Times on Dec. 17, 2010, that Congress cannot force someone to buy medical insurance because it can only regulate what we do. This assumes that medical care is something we can do without. But those who do not buy insurance almost invariably seek it and impose the cost on the rest of us. To avoid paying for their care, we would have to callously deny them treatment and watch them die at the hospital gates. The constitution does not require us to respect the right not to buy insurance only to force the rest of us either to buy it for others or deny it when it is needed. We do not want to become the kind of people that would deny someone care who is begging for it at the hospital and it cannot be that the only alternative to that scenario is that the rest of us have to pay for people who could, but do not, buy insurance to pay for their own care.
Libertarians believe it is a violation of individual liberty to force them to buy medical insurance. But it is equally a violation of individual liberty to make others pay for your medical care when you have the capacity to contribute to paying for it. And it is a violation of both liberty and humanity to suggest that if I do not want to pay for your care that I should simply refuse to help you. My own religious beliefs do not permit that.
Remember also that Medicare is based on the congressional powers to tax and spend. It is ironic indeed that conservatives who oppose the mandate believe the only constitutional way to achieve universal health insurance is through the public option that they deplored.