A US judge presiding over a copyright infringement case against Google has issued a decisive judgment which will have worldwide implications for users of the video-sharing internet site YouTube. Google has been ordered to hand over the full details of all of YouTube's users' viewing habits, in a judgment made in the course of a $1bn lawsuit. The suit was filed in California last March against Google, the owners of YouTube, by publishing and media giant Viacom. Viacom demanded that Google must hand over data about how people use the site, in order that Viacom could study it and prove that material that infringes copyright is routinely posted and watched by viewers. Viacom has now decided that it will accept the data in an anonymised form, however, the original and highly controversial order still stands and may form a precedent which poses a significant threat to data privacy worldwide.

Judge Louis Stanton ordered Google to reveal detailed viewing data relating to every single video clip uploaded to You Tube, along with the user names and IP addresses of both posters and viewers of the site. In particular, the order to reveal the IP address of users has caused concern. The IP address identifies individual computers connected to the internet, but cannot be connected to a name or address without the help of an internet service provider (“ISP”). If the ISPs (among them Virgin, AOL and BT) could be persuaded to yield the names and addresses connected to the IP addresses which have been revealed as a result of this judgment, the ramifications for YouTube's billions of users could have been be enormous. Google had fought the request on privacy grounds, and argued that it was not easy to hand over its viewing logs due to the sheer amount of data that they contained. Judge Stanton rejected these arguments suggesting that claims of practical difficulties were unfounded, particularly as while the amount of logging data was necessarily large, the technology existed for the contents of those logs to be copied onto certain hard drives.

In the course of the proceedings, an important judgment concerning the commercial value of source code for internet sites was also made. Viacom had also requested that Google should be required to disclose the source code of the YouTube site, but this was deemed a commercially sensitive piece of code that would reveal the inner workings of the site, and therefore was not disclosable. Viacom requested this evidence in order to support its claim that the YouTube source code could easily be adapted to filter out copyright protected material. By revealing this source code, Viacom would have easily been able to replicate YouTube’s format and used it for its own purposes, making this part of the judgment a valuable assertion of the value of copyright in source code for websites.

Google has consistently denied that YouTube infringes copyright, saying that it takes down protected videos from the site when asked by content owners. Viacom countered with the argument that the highest viewing figures are for illicitly-uploaded material, a charge which Google denied. By allowing Viacom access to the viewing data, the Judge has effectively allowed Viacom the chance to analyse the data and prove their arguments. Paradoxically, YouTube is frequently used by film studios, television production companies and record companies (such as those owned by Viacom) in order to "leak" new videos and new content to the vibrant and burgeoning online community of viewers, and use the internet in order to build a fan base. It is this aspect of the judgment which has proved most worrying to privacy commentators, who argue that media giants are seeking to “have their cake and eat it” by leaking material on sites such as YouTube in order to market their products, while at the same time holding the threat of onerous judgments such as these over the heads of the sites they can use to make spectacular profits.

Technology commentators have speculated that the latest judgment will be a blow to Google, who two years ago bought YouTube for $1.65bn. In that time, however, it has struggled towards profitability. YouTube's escalating bandwidth costs are estimated to exceed $1m a day, and the prospects of further copyright infringement judgments will not impress Google's shareholders. However, by virtue of YouTube, Google has effectively sewn up the global online video market, though in the UK the BBC's i Player is a significant rival. It is a portal to which viewers can access quite literally millions of videos, from movie trailers and episodes of popular television shows, to home videos.

Viacom’s decision to settle the case and allow Google to anonymise the IP addresses is perhaps disingenuous – Google vowed to appeal the judgment of Judge Stanton, arguing that it breached various privacy acts including the Video Rental Privacy Protection Act of 1988, passed after the rental habits of a Supreme Court Nominee were passed to a national paper and widely reported. By agreeing to settle, Viacom will have preserved this judgment as a damaging precedent, and Google may come to rue the decision to settle the matter.

So far, so interesting – but what are the implications for YouTube's millions of viewers worldwide? If the file-sharing websites and ISPs are in the future forced bow to pressure from media giants threatening legal action, they could be forced to reveal the personal data behind the IP addresses. This means that media and music companies who sue websites and demand the IP data could come into the possession of the detailed viewing and download habits of millions of people worldwide. With media companies already pursuing individuals who upload copyright-infringing material onto file sharing sites such as Napster and BitTorrent, this judgment could be the opening salvo in the world's largest ever misappropriation of data for the purposes of pursuing so-called “bedroom piracy”. The question for those in data protection is this – if a private dispute in California between two private companies can prove to be the key to the personal data of millions of individuals worldwide, how can legislation possibly respond?