Nintendo's aggressive stance against emulation is well-documented. Recent examples include the $2.4 million settlement with Yuzu emulator developers in March 2024, the October 2024 cessation of Ryujinx development following Nintendo's intervention, and the advice given to Dolphin emulator developers regarding a Steam release in 2023. The 2023 case against Gary Bowser, involving the sale of devices circumventing Nintendo Switch anti-piracy measures, resulted in a $14.5 million judgment.
A patent lawyer representing Nintendo recently shed light on the company's approach to piracy and emulation, highlighting the potential link between emulator use and software piracy. At Tokyo eSports Festa 2025, Koji Nishiura, a Nintendo patent attorney, explained that while emulators aren't inherently illegal, their use can become illegal depending on functionality. Specifically, emulators that copy game programs or disable console security measures may infringe on copyright.
This legal argument relies heavily on Japan's Unfair Competition Prevention Act (UCPA), limiting Nintendo's ability to pursue legal action internationally. The Nintendo DS "R4" card, which allowed for running pirated games, serves as a precedent. Nintendo's successful lawsuit against R4 manufacturers and resellers, resulting in a 2009 sales ban, demonstrates the company's willingness to leverage the UCPA.
Nishiura further emphasized that tools facilitating pirated software downloads within emulators, such as the 3DS "Freeshop" or Switch "Tinfoil," also violate copyright laws. Nintendo's lawsuit against Yuzu cited one million pirated copies of The Legend of Zelda: Tears of the Kingdom, linking the emulator's Patreon revenue to the distribution of pirated games.