A tax is a tax. A penalty is a penalty. A penalty can be imposed in the form of a tax. There can even be penalties imposed for the non-payment of taxes. When Congress calls a financial penalty on the economic decision of a person not to purchase some product a "penalty," they aren't doing so randomly nor are they doing it erroneously. The sanction IS a "penalty." How do we know this? We wouldn't have to pay it otherwise. It penalizes that particular economic decision -- and it imposes that penalty by USING the tax system. So, is the penalty ALSO a "tax?" Maybe. Roberts said so and let's face it, he's the Chief Justice so he is authorized by the Penumbra Clause to rewrite Congressional Acts. But tax or not, it most certainly IS a penalty.