At the Tokyo eSports Festa earlier this week patent attorney and deputy general manager of Nintendo’s intellectual property department, Koji Nishiura, agreed that the emulators are, technically, completely legal.

There are still a number of ways that emulators can violate the law. For example, the Nintendo Switch has certain “technical restriction measures” that prevent it from playing pirated games. If a Switch emulator seeks to bypass those measures, it opens itself up to legal trouble.

This means that while they are legal, emulator developers have to be careful.

Note that this discussion was based on Japanese law, but the same language is found in the DMCA Section 1201(a)(1)(A): “No person shall circumvent a technological measure that effectively controls access to a work protected under this title.” That law is more than 26 years old but the language remains in place.

Additionally, the specific programs a console uses, such as the home screen or menus, are subject to copyright protection. Copying those elements in an emulator could be illegal.

Nishiura stated that Nintendo shut down emulators around the globe for bypassing technological restriction measures, framing it as a way to protect developers. The company did something similar back in 2009, when it teamed up with 54 developers to shut down a company making a device that played pirated DS games.

Nishura also pointed out that emulators that direct users to pirated games or other copyrighted material are also in clear violation of the law. That appears to have been the case with Yuzu developer Tropic Haze, who is rumoured to have been internally sharing ROMs for the latest Switch titles.