See also Sega v Accolade.
Sega had implemented a measure to discourage unlicensed games for the Genesis/Megadrive. Upon boot, the console would ensure that the string "SEGA" was present at a certain memory location and then display that string as part of a longer message to the user asserting that the game was produced under license from [string]. The idea was that circumventing this would constitute trademark infringement.
Accolade reverse engineered and circumvented it. Sega sued for trademark infringement. Accolade eventually won. The whole thing only harmed consumers since by the time Sega implemented the measure there were already a bunch of games, both licensed and unlicensed, that did not pass the check.