"To begin with, are emulators illegal or not," Nishiura asks. "This is a point often debated. While you can't immediately claim that an emulator is illegal in itself, it can becom

Koji Nishiura, Nintendo's patent attorney, weighs in on the legality of video game emulators.

One of the key uses that has set Nintendo's alarm bells ringing in the past is when an emulator bypasses a console's "technical prevention methods" like encryption, says Nishiura. If an emulator does away with specific security measures like this, it is in breach of Japan’s Unfair Competition Prevention Act and you can expect a takedown to ensue.

Nishiura added that if the emulator also disables security measures like encryption, that could also be considered illegal. He said this counts for other methods such as flash carts, citing the use of Nintendo DS flash carts (such as the R4) which bypassed security by imitating a legitimate DS game.

Nishiura also emphasised the use of emulators is a problem for all developers making software for Nintendo devices, which is why the company is strengthening measures against such illegal tools.

Nintendo is famously litigious when it comes to emulators. In March 2024, developers of Nintendo Switch emulator Yuzu were ordered to pay $2.4 million in damages after a court settlement with Nintendo.

However, when you play the same game on your own PC or phone, using an emulator that Nintendo doesn’t own, would it still be legal? The Sony v. Connectix case created a precedent that makes emulation of video game consoles is legal, including copying its copyrighted BIOS.

One of the heads of Nintendo's intellectual property department gave a speech outlining what Nintendo views as illegal use of emulators.