France has passed a controversial law which could make Apple's iTunes service illegal. Despite being weakened in the parliamentary process, the law is still a major blow for Apple in a major European market.

The copyright law has been designed to prevent customers of a music shop being locked into one particular player device. Currently songs from iTunes can only be played on iPod devices.

The law was passed by both the French houses of parliament on Friday following amendments made by the upper house, the Senate. In its original form the law required any vendor to share the computing code behind their digital rights management (DRM) technologies.

This would have allowed songs to be played on any machine, but Apple argued that such a move would undermine the security of protected files and prove a boon for piracy. Apple has called the law in its original form "state sponsored piracy".

The Senate weakened the law, though, creating a loophole which would allow DRM to restrict a tune to a certain music player if that was the wish of the copyright holder. With labels' and artists' permission, then, Apple can continue to restrict iTunes purchases to iPod players.

The socialist and green parties in the French parliament have mounted a constitutional challenge to the new law in a process that could take some weeks. Should that fail the proposal will immediately become law.

"This text affirms a new principle, interoperability, which makes France a pioneer country in Europe," said France's culture minister, Renaud Donnedieu de Vabres, in parliament.

Other European countries may follow France's lead. The Norwegian consumer ombudsman has ruled that the DRM breaches competition rules and that it must change the technology. Cases in Sweden and Denmark are proceeding along similar lines.

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