/edit: I was WRONG. This is my memory failing me. I explain it further below, and apologize for wasting any time.
After the DMCA passed there was a case of a judge finding it legal to bypass DRM to make backup copies, but illegal to distribute the software used to do so. I have no idea if there was ever further clarification or new law about this. That was like 20 years ago. It was part of a case going after the company who was making the software, but the name slips my mind. I'll try to look it up if anyone cares enough and wants to look for something more than hearsay on a forum.