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 legal advice preventing a full Steam release of the Gamecube/Wii emulator Dolphin in 2023 due to Nintendo's pressure. The infamous 2023 case against Gary Bowser, who sold devices that bypassed Nintendo Switch anti-piracy measures, resulted in a $14.5 million judgment.

A Nintendo patent attorney, Koji Nishiura, recently shed light on the company's strategy at Tokyo eSports Festa 2025. While emulators aren't inherently illegal, Nishiura clarified that their use can become illegal under specific circumstances. Specifically, emulators that replicate game code or disable console security measures may infringe on copyright laws.

This legal action often relies on Japan's Unfair Competition Prevention Act (UCPA), which limits Nintendo's extraterritorial reach. The 2009 ban on the Nintendo DS R4 card, which allowed pirated game execution, serves as a precedent, highlighting Nintendo's success in leveraging the UCPA against manufacturers and resellers.

Nishiura also emphasized that tools facilitating pirated software downloads within emulators, termed "reach apps" in Japanese law, violate copyright. Examples include the 3DS's Freeshop and the Switch's Tinfoil.

Nintendo's lawsuit against Yuzu highlighted the alleged one million pirated copies of The Legend of Zelda: Tears of the Kingdom, citing the emulator's Patreon revenue ($30,000 monthly) generated through premium features and early access. This underscores Nintendo's focus on financial losses stemming from emulation and its associated piracy.