R4 cartridges, which are used to play pirated copies of games on the Nintendo DS, are now illegal in the UK.
A judge ruled against R4 company Playables Limited and Wai Dat Chan, making it illegal to import, advertise and sell R4 carts in Britain.
The "first-ever" judgement was made after the London High Court ruled the carts were illegal because they bypass the DS's security measures in order to run games.
"Nintendo promotes and fosters game development and creativity, and strongly supports the game developers who legitimately create new and innovative applications," Nintendo said in a statement.
"Nintendo initiates these actions not only on its own behalf, but also on behalf of over 1,400 video game-development companies that depend on legitimate sales of games for their survival.
In the U.K. alone, there have been over 100,000 game copying devices seized since 2009, Nintendo said.
Playables Limited and Wai Dat Chan argued that game copiers were lawful because they allow for the play of "homebrew" applications. Obviously that didn't work.