In the recent Supreme Court ruling on the Affordable Health Care Act, the court held that applying a penalty for not participating in commerce was unconstitutional in that it exceeded the scope of the Constitution's Commerce Clause, but that the act as a whole was constitutional because the penalty was actually a tax under Congress' taxing authority. The fact that this would have the same effect as a penalty for nonparticipation in commerce violates a principle of the Outcome Model of Procedural Justice, which states, "if two procedures produced equivalent outcomes, then they are equally just" (or unjust).
How can Congress be barred from imposing regulations on nonparticipation in commerce while it is given the power to impose a tax on those who fail to participate? Expanding Congress' power to tax is the equivalent of expanding its authority under the Commerce Clause, and they are therefore, both equally just -- or equally unjust.
A difference that makes no difference is no difference.