A scene from the Oscar-winning film Dallas Buyers Club Photo Credit: Anne Marie Fox / Focus Features

Dallas Buyers Club (DBC) LLC has won its copyright battle against iiNet and other Australian internet service providers, with the Federal Court ordering the ISPs to reveal the names and addresses of 4726 customers who allegedly downloaded the film illegally.

The company is now expected to be writing to all of the customers involved, although it’s not yet clear what demands – if any – they might make. They could threaten to sue for copyright infringement and offer to settle instead.

“I will impose upon the applicants a condition that this information only be used for the purposes of recovering compensation for the infringements,” Justice Nye Perram said in the ruling.

The letter they send will have to be vetted by the court.

“They are to submit to me a draft of any letter they propose to send to account holders associated with the IP addresses which have been identified,” Justice Perram said.

In the US, the studio filed lawsuits targeting more than 1000 people who allegedly downloaded the film via torrent client BitTorrent, seeking up to US$5000 (AU$6500).

The film’s copyright holders made a preliminary discovery application to the court seeking the details of internet users it claims were engaged in copyright piracy via peer-to-peer programs.

DBC used German software called MaverickEye to find nearly 5000 instances of online piracy, between April 2 and May 27, 2014. The company claimed during the February court case that another 6,000 would be detected if it ran the tracking software again. MaverickEye collects IP addresses in torrent swarms, but the information is useless without contact details, which led to the application to force ISPs to hand over customer contacts.

iiNet opposed the application. The decision comes as the Australian parliament considers anti-online piracy measures including the power for copyright owners to apply for a court injunction to block overseas websites involved in piracy.

The landmark decision includes Dodo, Internode, Amnet Broadband, Adam Internet and Wideband Networks customers and sets a major precedent for piracy law in Australia.

The ISPs pushed to stop the studio engaging in US-style “speculative invoicing”, where companies threaten to sue for damages of up to AU$200,000, but instead settle for a few thousand dollars.

Justice Perram said that he was “comfortably satisfied that the downloading of a sliver of the film from a single IP address provides strong circumstantial evidence that the user was infringing copyright”.

iiNet has 28 days to decide if it will appeal the decision before the Full Court.

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