An editor in court. A director in exile. An infamous murder. Everything is in place for the trial drama of the decade

Debra Tate will be called to give evidence for Polanski - Sharon's widower - as he takes groundbreaking libel action against the US magazine's publisher, Condé Nast, in London's High Court over the publication of an alleged slur which he believes to imply he betrayed her memory.

It was Debra, 53, who 36 years ago broke the news to Polanski that his wife had been killed, stabbed to death by the disciples of small-time cult leader Charles Manson in a barbaric spree in Beverly Hills that shocked the world. Polanski was out of the country at the time.

The libel case will make legal history as the first to be brought by someone who will not actually attend the hearings, which are expected to last for five days. Instead he will remain in Paris, where he has lived for nearly three decades, and appear via a video link over which he will give evidence, be questioned and monitor the hearing.

Polanski will not travel to the UK because of the likelihood that he will be extradited to the US and imprisoned. He fled America, where his career was soaring, in 1977 after he admitted having sex with 13-year-old Samantha Geimer, who has since publicly forgiven him.

The case will revolve around Vanity Fair's claim in an article three years ago that Polanski made sexual advances towards a woman he met in a New York restaurant around the time of his wife's burial and suggested that he could make her "the next Sharon Tate". It is an accusation which Polanski vigorously denies. It is said to have left him "utterly distraught".

Polanski chose to bring the case against the magazine, edited by the publishing legend Graydon Carter, in the UK rather than the US because the libel laws are less restrictive. Before the case got to this stage, Polanski had to go all the way to the House of Lords to secure a historic ruling that he could give his evidence from Paris.

Carter has become a flamboyant giant of the magazine world since taking over Vanity Fair in 1992. He is chauffeured to his nightly meetings with Manhattan's glitterati, is constantly decked out in finely tailored suits and throws the most keenly attended post-Oscars party.

Witness statements have been prepared by the actresses Catherine Deneuve, star of his film Repulsion, and Nastassja Kinski, who took the title role in Tess, although they will not be joining the cast list in court. However, Mia Farrow, who took the lead role in his 1968 film Rosemary's Baby, will appear in court after being called by Polanski's legal team, the leading media law firm Schillings.

Debra Tate, who has fought for years to protect her sister's memory by maintaining her website and campaigning to keep her killers behind bars, will fly in from her home in Riverside County, California, to speak for Polanski. She is the last surviving spokeswoman for the family; her mother, Doris, and sister, Patty, have both died of cancer. Her father, Paul, died in May.

Although Polanski, 71, made his early reputation in Britain and Hollywood, he has had to rebuild his career in mainland Europe to avoid the risk of extradition. Rural France doubled for Thomas Hardy's Wessex in Polanski's 1979 adaptation of Tess of the d'Urbervilles.

He won an Oscar in 2003 for The Pianist, but as he was unable to attend the ceremony, Harrison Ford collected the trophy. The hearing is due to begin on Monday 18 July.