Fear of corporate surveillance is a topic that has been rattling around for years. This week, it emerged that spy software is the latest weapon in the entertainment industry's war against copyright pirates. But as file-trading peer-to-peer (P2P) networks like Napster become increasingly popular, can corporations force people to obey laws they don't believe in?

News site 7amnews.com has exposed a piece of software called Media Tracker which, it alleges, the entertainment industry is using to spy on individuals using P2P networks. Media Tracker can tell exactly what pirated music, video or software files you are trading.

It can trace your identity and lawyers can then send out a cautionary letter to your Internet service provider (ISP), insisting that you stop sharing copyrighted material or potentially face prosecution. Industry lawyers have contacted ISPs more than one hundred times in the past few weeks asking them to exclude individuals involved in file trading.

Unable to prosecute every user, the entertainment industry's options are limited. Perhaps by making examples of a few high-profile users, it might intimidate others into stopping. The long-term success of any surveillance campaign would depend on the co-operation of ISPs, which are unlikely to want to become a global Internet police force.

If ISPs start accepting responsibility for what is held on subscribers' hard drives, it will not only dramatically increase their responsibilities but also severely compromise the privacy of their customers, who will simply leave and join another less-discriminating ISP.

Even if the entertainment industry lawyers overcome these obstacles and manage to find a practical way of using the technology, it may already be out of date and unable to cope with the most recent P2P innovations. New file trading networks such as Freenet http://freenet.sourceforge.net are totally decentralised and spread files across all the computers involved. There is no central hub or index, and no way for individual users to tell what is being stored on their computers. No one keeps track of users and this makes it nearly impossible for even sophisticated programs to track who is sharing what with whom.

Unless Internet users decide to stop voluntarily, there seems very little the entertainment industry can do to force them.