BT has been given 14 days to block the Newzbin 2 file-sharing site, and must cover the costs of the technical measures it puts in place, in an order clarifying the High Court's initial ruling.
The decision represents the first time that an internet service provider (ISP) has been forced to block access to a site, and sets a precedent that could be used to implement similar measures on other sites and ISPs.
The ruling is also noteworthy as it was made under the Copyright, Design and Patents Act, rather than the Digital Economy Act (DEA) which was developed in part to respond to online piracy, and so renders a large portion of the DEA irrelevant.
Chris Marcich, president of the Motion Picture Association, which brought the case against BT, claimed that the organisation was forced to take the action to protect the creative industries from piracy.
"This is a win for the creative sector. Securing the intervention of the ISPs was the only way to put the commercial pirates out of reach for the majority of consumers," he said.
"This move means that we can invest more in our own digital offerings, delivering higher quality and more variety of products to the consumer."
Spyro Markesinis, vice president for business and legal affairs at Momentum Pictures, the distributor of The King's Speech, one of the films being infringed on the site, said that the ruling is vital to ensure the success of the film industry.
"There is a real concern that films such as The King's Speech will not be made if these rogue sites are allowed to undermine legitimate sales and syphon off illegal profits," he said.
"We will continue to work not only with government and the ISPs to stop piracy, but with our digital partners to bring the best, most attractive offers to consumers via legitimate channels."
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