McConnell's attack on health reform is 'absurd'

From Greg Sargent of the Washington Post:

As you may have heard, Mitch McConnell has thrown in his lot with states suing to overturn Obamacare, filing a friend-of-the-court brief arguing that the individual mandate is unconstitutional.

I just checked in with a constitutional law professor -- this seemed like a good hook to ask an expert to take a look at this claim, since it's so widespread -- and he dismissed McConnell's argument as "absurd."