The European Court of Justice has ruled that ISPs cannot be forced to hand over the personal details of those under suspicion of digital piracy.

A case brought by Spanish music organisation Promusicae had demanded the account details of several Telefónica users which it had accused of sharing music illegally using the Kazaa peer-to-peer network.

But the court found that, under present law, the right of the individual to privacy is guaranteed, and backed Telefónica in refusing to hand over the details.

However, the European court stated that it is up to individual member states to enact laws for their own countries.

"The Court points out that the present reference for a preliminary ruling raises the question of the need to reconcile the requirements of the protection of different fundamental rights, namely the right to respect for private life on the one hand and the rights to protection of property and to an effective remedy on the other," the ruling reads.

"The Court concludes that the member states must, when transposing the directives on intellectual property and the protection of personal data, rely on an interpretation of those directives which allow a fair balance to be struck between the various fundamental rights protected by the Community legal order.

"Further, when implementing the measures transposing those directives, the authorities and courts of the member states must not only interpret their national law in a manner consistent with the directives, but make sure that they do not rely on an interpretation of them which would be in conflict with those fundamental rights or with the other general principles of Community law, such as the principle of proportionality."

The judgement effectively leaves it up to European member states to determine their own laws on personal privacy.

The finding was welcomed by the music industry. "The European Court has confirmed the need to have effective tools to tackle piracy," said John Kennedy, chairman of the International Federation of the Phonographic Industry.

"The judgement means that music rights owners can still take action to enforce their civil rights, and has sent out a clear signal that member states have to get the right balance between privacy and enforcement of intellectual property rights and that intellectual property rights can neither be ignored nor neglected."