Does the battle against child pornography justify suing mainstream Internet companies and undermining the right to free speech?
The question goes to the heart of the international debate about how to regulate the Internet. It is proving a thorny issue to resolve, creating serious legal and ethical headaches for governments and the industry alike.
Companies offering access to the Internet claim they are being caught in a cat and mouse legal battle between police forces and pornographers.
The industry won a landmark case in Germany last month when the courts threw out a guilty verdict against a former head of the German arm of CompuServe, an Internet service provider. Felix Somm had been accused of complicity in distributing illegal materials because he had failed to block access to news groups - internet message boards - featuring child pornography.
The earlier ruling against Mr Somm triggered fears of widespread censorship on the net, and ISPs rushed to reduce their potential liability.
CompuServe initially blocked access to 200 message boards, before reinstating access to all but five after an outcry from subscribers.
Such fears have not been entirely quelled by Mr Somm's acquittal. Governments are still trying to pin some degree of responsibility on ISPs as a way of curbing illegal cyberporn.
In Australia, for example, a new act coming into force in January will allow the Australian Broadcasting Corporation to serve notice on ISPs to take action on prohibited content - material banned under the coun try's existing broadcasting classification system. ISPs will be forced to restrict access to the banned material, even if it is being hosted outside Australia, or face high penalties.
It is easy to see the attraction to governments of making ISPs liable. As a report commissioned by the British government pointed out last year, the originators of illegal cyberporn may well be "unidentifiable, untraceable, impoverished or beyond the reach of the courts, leaving industry players as obvious potential targets for responsibility".
But there are drawbacks to trying to police the net by making ISPs responsible for internet content. The first argument, which helped sway the German courts, is a practical one - big ISPs cannot be expected to vet the tens of thousands of web pages and millions of messages on their systems. Most providers argue their position is much closer to a post office, acting as a conduit for information, rather than a publisher.
Forcing ISPs to accept liability inevitably reduces the Internet's value as a medium for the free flow of information. Faced with a complaint that could lead to damages, a provider will tend to pull the offending site, even if the objection to it may be spurious.
The Supreme Court overturned key provisions of the Communications Decency Act in 1997 on the grounds that they clashed with the constitutional right to freedom of expression. "The act was draconian - it effectively banned all pornography and even, in some cases, information on abortions," says Mr Lars Davies, a research fellow at the University of London.
In Europe, governments are trying to encourage voluntary ways of dealing with cyberporn. The European Commission has drafted an e-commerce directive that would make ISPs potentially liable only if they were acting as host for material they knew was illegal.
