New documents filed Monday, February 26 reveal that videogame giant Nintendo is taking action against the creators of the popular emulator tool Yuzu.

The copyright infringement filing, from Nintendo of America, states that the Yuzu tool (from developer Tropic Haze LLC) illegally circumvents the software encryption and copyright protection systems of Nintendo Switch titles, and thus facilitates piracy and infringes copyright under the Digital Millennium Copyright Act (DMCA).

Nintendo alleges that Tropic Haze’s free Yuzu emulator tool unlawfully allows pirated Switch games to be played on PCs and other devices, bypassing Nintendo’s protection measures.

The official Yuzu website suggests that the tool is to be used with software you yourself own: “You are legally required to dump your games from your Nintendo Switch” — but it’s common knowledge, that this is not how these tools are primarily used.