Lawyers for Google are expected to challenge Italy's right to try Google executives at a hearing on Tuesday, in a trial seen as a test case over attempts to "police" web content.

Google lawyers hope that the case will be thrown out. Google is accused at the trial, which opened last month (February), of violating privacy laws after a three-minute mobile phone video showing four youths in Turin tormenting a classmate with Down's syndrome was posted on the Google Italy site.

The centre-right government of Silvio Berlusconi is using Italy's current chairmanship of the G8 to propose laws which would force internet service providers (ISPs) to block access to sites with "objectionable content".

The family of the boy at the centre of the trial has withdrawn from the case. However, the presiding judge, Oscar Magi, has instead accepted as the plaintiffs both Milan city council and Vivi Down, an association representing the interests of people with Down's syndrome.

Guido Camera, the lawyer representing the Vivi Down association, which originally drew attention to the existence of the video in September 2006, told The Times he understood Google would challenge the Italian courts' jurisdiction in the case. Only a handful of Google's 20,000 worldwide employees work in Italy, and Google's headquarters are in California.

It is understood that Tuesday's two-hour hearing will therefore hear arguments over whether the trial should be held in Italy at all, and if so whether it should be moved from Milan to Turin, where the victim of the bullying lives, or Rome, the capital.

Google says it removed the offending video within 24 hours of receiving complaints, but the Milan public prosecutor, Francesco Cajani, decided Google had broken the law by allowing the video on to its site at all. He claimed the video had remained online for two months in 2006 and that Google had failed to react to complaints.

Those accused are David Drummond, Google's chief legal officer; Peter Fleischer, the company's global privacy counsel; George Reyes, former chief financial officer; and Arvind Desikan, former head of Google Video Europe. They face up to three years in jail if convicted.

Last month (February) a lawyer for the boy and his family, said "The decision to withdraw from the case has been taken because Google officials have not only expressed their solidarity over what happened but have also taken concrete actions that show their sensitivity to the problems of handicapped people and the grave problem of bullying".

Mr Camera said it was not known if the family of the boy had received compensation. The four teenagers who builled the victim were were sentenced to community service by a court for minors in Piedmont, of which Turin is the capital.

The trial could set a precedent for providers of services that allow users to post content online. Italian law on the media - television and newspapers as well as the Internet - states that content providers are responsible for third-party content. This raises the question of whether a website is a "publication" for whose content providers are responsible by law in the same way as a TV channel or a newspaper or magazine.

Giuliano Pisapia, one of the Google defence lawyers, said it was impossible for Google to monitor everything that appeared on its video site, and that the Milan prosecutors' move amounted to censorship. "Google is a search engine, not a newspaper" he said. Google said that "seeking to hold neutral platforms liable for content posted on them is a direct attack on a free, open Internet."

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