Tums,
When halacha and secular law conflict in dinei momonus, halacha is controlling.
Of course, but it doesn’t have to be a conflict. My thinking is as follows (and I really don’t know if there’s any validity to this at all):
If fair usage laws do not allow someone the right to sell a CD without the ability to use it “fairly”, such as copying for personal use, then maybe halacha will therefore invalidate that part of the “sale”.