A High Court has ruled that devices that allow gamers to play pirated video games are illegal in the UK.
The ruling specifically targets a range of popular devices which can be used to store and play copied games on the Nintedo DS handheld console.
The ruling says "game copiers" are illegal to import, advertise and sell in the UK.
The defendants - Playables Limited and Wai Dat Chan - had argued that they allow gamers to play home-made games.
"The mere fact that the device can be used for a non-infringing purpose is not a defence," read the ruling by Justice Floyd.
Nintendo said it was "pleased that the court was not persuaded by the defendant's arguments, claiming that game copiers are lawful, as they allow for the play of 'homebrew' applications".
"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," it said in a statement.
Playables Limited and Mr Chan did not respond to requests for comment.
This UK judgment follows a similar ruling in the Netherlands earlier in July.
The Hague District Court ruled that 11 Dutch online retailers acted unlawfully by importing and selling game copiers for use with Nintendo DS and modification chips for use with Wii.
Game copiers are designed to fit into the game cartridge of Nintendo's DS. Games can then be loaded from memory cards.
The chips circumvent the protection measures Nintendo has built into its DS consoles, enabling illegally pirated games to be downloaded online and stored on a chip.
Other gamers use them to store and load homemade games or, as they can hold multiple games, to store their entire collection of titles in a portable format.
They are sold for as little as £10.
The ruling said that the defendants had imported nine different devices on a "large scale".
"HMRC and Trading Standards have seized more than 165,000 game copiers intended for the defendants," it read.
"The economic effect on Nintendo of the trade in these devices is substantial as each accused device can store and play copies of many Nintendo DS games."