This isn't enacting a law, though. This is changing the interpretation of the constitution. Prior to this, the interpretation was that the framers' intent was for citizens to be governed by the laws of their own state, now it's not. Let the chips fall where they may.
I don't think the distinction between legislative and common law is really meaningful in this case. A judge making a decision in a case like this is bringing a new law into existence.
Suppose I the owner of a small retailer based out of Oregon but have a location in Ohio. Should I be exempt from collecting sales tax simply because my company is registered and HQ'd in Oregon? The previous ruling was no, Ohio has the right to require my company to collect sales tax for sales in Ohio, but the ruling required that my company have a physical presence in the state. All that happened today was that the requirement to be physically present was dropped.
I mean the law is fairly narrowly scoped and certainly doesn't give states a blank check to write laws for citizens of other states.
