Specifically Chemerinsky addresses claims from some healthcare reform critics that requiring all Americans to either obtain healthcare insurance or pay a tax is constitutionally suspect.
First, they say the requirement is beyond the scope of Congress' powers. And second, they say that people have a right to be uninsured and that requiring them to buy health insurance violates individual liberty. Neither argument has the slightest merit from a constitutional perspective.
Congress has broad power to tax and spend for the general welfare. In the last 70 years, no federal taxing or spending program has been declared to exceed the scope of Congress' power. The ability in particular of Congress to tax people to spend money for health coverage has been long established with programs such as Medicare and Medicaid.
Chemerinsky's entire column is here.