Comment Workaround (Score 1) 24
A local or state cop is investigating a case but he can't quite justify a warrant, but he's all but sure the guy is guilty. And oh by the way, the internet was involved somehow, making it technically a federal crime too, "because internet" (technically, "because interstate commerce," but I digress).
He calls up his friends at the federal prosecutor's office and says "Can you take this case? I've done most of the legwork but I'm stymied by this state law that says I can't buy data from a data broker and I can't quite justify getting a warrant, but you can easily buy the data from the data broker which should make this case a slam-dunk."
Assuming the local/state prosecutor has a good reputation/relationship with the federal DA and the federal DA is interested in taking this type of case in the first place, you now have a "workaround" to the state law.