Sales of the R4 cartridge, which allows users to play pirated DS games, have been outlawed in Japan.
According to Kotaku, the Tokyo District Court has granted an injunction against the Chinese manufacturers who produce the R4. As a result, it's officially illegal to sell the cart, and the R4 has already disappeared from shops.
Square Enix, Nintendo and Capcom have issued statements pointing out how illegal sales of the R4 are now, just to be sure, and saying they'll continue to chase down anyone producing similar devices.
It's still legal to buy an R4 in this country, though obviously downloading pirate games is bad and wrong. Who knows, perhaps our lawmakers will follow Japan's lead in future.