It seems I had swapped Tengen and Accolade in my memory. I am thinking of Sega v. Accolade.
The Ninth Circuit reversed the district court's order and ruled that Accolade's use of reverse engineering to publish Genesis titles was protected under fair use, and that its alleged violation of Sega trademarks was the fault of Sega.
Both of those cases were about whether reverse engineering violates copyright law, they're not really relevant to the antitrust claims Epic is alleging in their lawsuits.
