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 high-profile 2023 case against Gary Bowser, who sold devices circumventing 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 legal strategy at Tokyo eSports Festa 2025. While acknowledging that emulators aren't inherently illegal, Nishiura emphasized that their use can become illegal under specific circumstances. Specifically, emulators that copy game programs or disable console security mechanisms may infringe on copyright.

This legal argument relies heavily on Japan's Unfair Competition Prevention Act (UCPA), which limits Nintendo's extraterritorial reach. The R4 card for Nintendo DS, which allowed pirated game execution, serves as a precedent. Nintendo successfully used the UCPA to ban R4 sales in 2009.

Nishiura also highlighted the illegality of "reach apps"—third-party tools facilitating pirated software downloads within emulators. Examples include the 3DS's "Freeshop" and the Switch's "Tinfoil." These tools, he argued, violate copyright law.

The Yuzu lawsuit further illustrates Nintendo's approach. Nintendo alleged one million instances of The Legend of Zelda: Tears of the Kingdom piracy facilitated by Yuzu, citing the emulator's Patreon revenue ($30,000 monthly) generated from providing premium features, including early access to games.