The burden of proof, of course, would be on Apple to prove that their FairPlay-applying software was developed using knowledge gained from reverse engineering and not through other means. This may be difficult.
This is an extremely interesting case. The EFF has a
page on this case.
The initial decisions by the Missouri courts ruled that click-thru licenses are enforceable without UCITA adoption. They also ruled that there were DMCA violations, because the bnetd server can be used to bypass the Diablo CD key restrictions.
The ruling was
upheld by the 8th Circuit court. One of their key arguments is that the bnetd server doesn't validate CD keys or check for duplicate keys - meaning the program can be used to enable piracy.
Whether this is applicable to the FairPlay debate is arguable. In the Blizzard case, the program created (using reverse engineering and EULA violation) could be (and was) used to enable piracy. If the Navio software can only be used to apply compatible DRM to new documents, and not remove DRM from existing documents, then the precedent from the Blizzard case should not be applicable.
The ruling about click-thru licenses is much more disturbing, but this is still a matter of state law, not federal. I strongly disagree with the Missouri court's conclusion that the UCC makes them legally binding - the UCITA was drafted specifically for the purpose of making them binding, which implies that they are not in its absence.