The R4 device and its ilk allow unauthorised programs to run on Nintendo DS handhelds--contentiously letting owners easily play pirated software and games. They will now become illegal to import, advertise or sell anywhere in the UK.
"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," the company said in a statement.
However, this ruling will also impact upon the 'homebrew' scene. Enthusiast programmers have used emulator cards to bring everything from media players and paint programs to Wikipedia readers and brand new games to the DS.
The R4 and similar devices were declared illegal to sell in Japan last year.