It was bound to happen. The defendants of the case were keen to point out that these devices (such as the infamous R4 card) could be used for legal purposes, such as allowing users to play homemade games. However the High Court mentioned this in a statement...
The court affirmed that game copiers first circumvent Nintendo's security systems before any non-infringing application can be played on Nintendo's handheld products [BBC News]Nintendo have been working through various court procedures all across the globe to make these devices illegal. Only this year, back in July, the Netherlands also banned the sale of R4 cards.
It's no surprise that Nintendo weren't happy. Grand Theft Auto: Chinatown Wars received very impressive scores from various magazines and websites, only to end up as the worse selling GTA game by some margin for this generation. Although it has been argued that adult rated (18+) titles don't have much of an audience on the DS compared to home consoles and the PSP (of which they do have a point) many industry professionals were quick to point towards torrent sites that were hosting a downloadable copy of the title as the main reason for its poor sales, which include the CEO of Take-Two, the publisher of Rockstar's GTA games Ben Feder:
As of February 2010, Chinatown Wars’ unit sales in the US represented nearly 50 per cent of the unit sales of all M-rated DS titles in the history of the platform.“At the same time, the handheld market is currently challenged by weak demand and by piracy. Piracy is a real and present danger for our industry and must be addressed, especially in the handheld market. The commercial performance of Chinatown Wars has certainly suffered at the hands of piracy [MCV]Although this ruling is a victory for Nintendo, I'm sad to say it's all a little too late. The majority of these devices work perfectly on the DS Lite, but do not work on the newer DS iterations, the DSi and its bigger brother the DSi XL. Sadly, too many of the previous generation of DS owners already have one of these cards, and with the lack on compatibility to play them on the newer styles of DS has probably seen the interest in these cards decline anyway.