To be clear, I'm not a huge fan MDY v. Blizzard, but just so we're all on the same page with respect to the one of the bigger cases in this area, MDY was a suit involving the vendors of a bot program ("Glider") for WoW. The Court of Appeals for the 9th Circuit (not controlling over a NC district court, but highly influential) initially held that use of the bot was not copyright infringement. Their reasoning went something like this:
1. Playing software on your computer makes a "copy" of the software in your RAM for copyright purposes (this is based in part on some unfortunate precedent)
2. Therefore, in order to evade copyright liability, you need to be an owner or a licensee of the software.
3. WoW players are licensees.
4. Some license terms are conditions (limiting the scope of the license). Other license terms are mere covenants, and violating them does not implicate copyright.
5. The anti-bot and prohibition on third-party software provisions in WoW's Terms of Use are mere covenants.
6. Glider use does not violate a condition in WoW's terms of use.
7. Even where a user violates a condition, the user is not automatically a copyright infringer. The breach of the condition must have some nexus to the copyright holders' statutory rights (e.g., if I license you to copy one and only one copy of my book, with the caveat that you cannot read the last ten pages, and you make the copy but also read the last 10 pages, I can sue you for breach of contract but not copyright infringement because reading does not implicate one of my exclusive rights).
8. Glider use does not implicate any of Blizzard's statutory rights.
BUT then the court considered whether circumventing WoW's anti-cheating program (which blocked server access to those using bots) violated the DMCA.
9. DMCA § 1201(a) prohibits the circumvention of any technological measure that effectively controls access to a protected work *whether or not the circumvention actually involves or leads to copyright infringement* (this is a controversial reading of the DMCA--a badly drafted statute--and one of the main reasons the DMCA is bad)
10. DMCA § 1201(a)(2) prohibits trafficking in technologies that are intended to circumvent technological measures that effectively control access to a protected work.
11. WoW's anti-cheating program effectively controls access to WoW's dynamic, non-literal elements (i.e. the actual game experience)
12. MDY therefore violated section 1201(a)(2) by marketing and selling a program designed to circumvent a device that effectively controlled access to a protected work.