On the surface, this looks like a win for conservatives and a restriction on Congress’ commerce power. It isn’t. The reason isn’t that the four conservatives, including Justice Anthony Kennedy, deliberately chose not to join Roberts’s opinion (maybe because they were angry at him for breaking ranks). It is that in the real world, as opposed to the realm of legal theory, there is no meaningful difference between action and inaction. In the future, Congress can simply phrase Commerce Clause commands in the affirmative.
Consider the Civil Rights Act: Does it require public businesses to serve customers regardless of race? Or does it prohibit them from refusing to serve customers on the basis of race? See the difference? Oh yes, there isn’t one.
If that weren’t enough, there is also Congress’s power to tax, on which Roberts relied. If Congress wants to penalize you for not doing something in the future, it can impose a tax. And as Roberts’s ACA decision affirmed explicitly, Congress doesn’t even have to call it a tax. In short, in practical terms, Congress has no less power than it had prior to the decision.
We have been down this road of pseudo-limitations on the commerce power before.