"If he had simply put a tax increase in the bill to pay for it, it would be totally constitutional." Maybe. If the tax were not contingent on health-care ownership, then it would probably be constitutional but it would also fail to serve the specific purpose that the individual mandate is supposed to serve - avoiding having people opt-in and opt-out of being insured based on how sick they are at any given moment. If the mandate's penalty was simply reframed as a tax increase, then it might be constitutional, or it might have been found to be a pretextual attempt to circumvent the kind of constitutional restrictions which motivated today's verdict - you can't, for example, get away with taxing people who engage in speech you disapprove of rather than simply banning it and running afoul of first amendment protections. But the main point is that if the individual mandate were actually framed as a tax increase that would largely fall on lower/middle-class individuals, then it simply wouldn't have passed through Congress.