R4 carts and other similar devices that enable illegal roms to be played on the Nintendo DS have been banned in the UK.
According to MCV, London's High Court has ruled in favour of Nintendo, making the homebrew devices illegal in the UK, preventing retailers from importing and selling the hardware. Defendants Wai Dat Chan and Playables Limited argued that the R4 allowed users to run homebrew applications, but was made redundant as the R4 must bypass Nintendo’s security before it can work.
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.