A year and a half after Marius Borg Høiby was arrested by police over a violent episode at a woman's flat's in Oslo, the son of Norway's crown princess has gone on trial, in the biggest case to come to court here for years.

Høiby pleaded not guilty to four charges of rape, as the public prosecutor read out the 38 charges against him.

The seven-week trial opened at Oslo district court against a backdrop of almost daily revelations surrounding him and his mother, Crown Princess Mette-Marit.

The crown princess is facing increasing criticism after it emerged that she was cited in hundreds of emails showing extensive contacts with the late US sex offender Jeffrey Epstein.

She has admitted showing "poor judgement", but the fallout has already begun, with one organisation dropping her as patron for its annual prize.

On the eve of the trial it emerged her 29-year-old son had been detained again, in circumstances not unlike his initial arrest, on suspicion of assault, making threats with a knife and violating a restraining order.

As police have placed him on remand for four weeks, he began the trial in custody.

His defence team intends to appeal against the decision.

Marius Borg Høiby appeared in court wearing a brown sweater and white T-shirt, green trousers and glasses, his blond hair cut short. Heavy court restrictions have been imposed on the trial, with a ban on any pictures of the defendant inside or outside court. The judge broke into English at one point to emphasise the rules to international media.

As the charges against him were read out, he pleaded not guilty to the four accusations of rape, speaking very quietly.

He partially admitted charges relating to a woman in Frogner in western Oslo in August 2024, admitting bodily harm but denying abuse, He admitted several other charges, including violating a restraining order, transporting marijuana and speeding. At times he fiddled with a bracelet as public prosecutor Sturla Henriksbø detailed the charges against him.

Sitting opposite, to the right of the prosecutor, were some of the women named as victims in the case. The court has banned any detail that might identify the four women involved - a point underlined by the judge as proceedings opened.

The prosecutor set out details of the rape charges, alleging that the first took place during an after-party in December 2018 in the basement of the defendant's parents' house when he was 21.

All four are alleged to have have taken place when the women were either asleep or incapacitated.

The royal family will not attend the trial in Courtroom 250 at Oslo district court which has attracted enormous interest throughout Norway and beyond.

Commentators do not see that as particularly surprising, with King Harald V and Queen Sonja heading to the Winter Olympics in Italy later this week, but it adds to a sense of isolation surrounding Crown Prince Haakon's stepson.

Marius Borg Høiby was born four years before Mette-Marit married the crown prince, and although he is seen as a close member of the family he is not part of the royal family itself and not a public figure.

He faces an array of 38 charges:

• rape with sexual intercourse while a woman was unconscious in October 2023
• three counts of rape by sexual assault on incapacitated women - considered rape in Norway - in December 2018, March 2024 and November 2024
• six counts of sexually offensive conduct without consent - including filming of victims
• causing bodily harm
• repeatedly abusing a current or ex-partner through threats, coercion or violence
• violating a restraining order against him
• transporting 3.5kg of marijuana
• speeding

Some of the charges involving abuse and threats in August 2024 relate to the so-called "Frogner woman", and it is understood that his latest arrest is linked to her too.

He is expected to give evidence for the first time on Wednesday. The case will be decided by three judges - if they find him guilty he could go to jail for at least 10 years.

His mother suffers from a serious lung condition and has difficulty breathing. But it is not her health that has become the talk of Norway in recent days, rather her name cited in more than 900 emails published by the US Department of Justice late last week.

The tone suggests a future queen of Norway exchanging messages with her guard down, even though she knows she is talking to a registered sex offender who had spent time in jail. It has also emerged she spent four days at his home in Florida when he was not present.

The Sex and Society foundation, which focuses on sexual and reproductive rights, has said it no longer wants Mette-Marit to act as high patron for its annual Shameless Prize, because what had emerged was incompatible with what it stood for.

The crown princess is Norway's future queen, and the decision will come as a blow to her reputation.

Prime Minister Jonas Gahr Støre urged Mette-Marit to "explain the extent of the contacts that have taken place".

Caroline Vagle, who is royal expert for celebrity-magazine See and Hear, believes these revelations will follow the crown princess for the rest of her life.

"The Norwegian public is shocked and disappointed, and I have to say I agree," she says. "The only right course of action now is to put all the cards on the table."

Ole-Jørgen Schulsrud-Hansen, a historian and royal correspondent for Norway's TV2, believes the princess's advisers and wider royal court should have known she was exchanging messages with Epstein and stopped it happening.

"In extension of that you also ask the foreign office. They are in place to protect Norway's standing internationally, and this is hurting that image internationally," he told the BBC.

Norway's royal family remains very popular, with a Norstat opinion poll not long ago suggesting 73% were in favour of it.

However, the leader of Norway's Green Party, Arild Hermstad, who is a republican says the email exchanges point to a monarchy that is not working: "It really puts not only the royal family in a big squeeze, but also for Norway itself, how do you actually solve this? At least she has to be very honest and frank."

By coincidence, Norwegian MPs vote on Tuesday on a motion that republicans submit by tradition every few years, although no-one expects it to attract much support.

Nevertheless Hermstad believes many MPs are sensitive to the future of the royal house. "It's hard to imagine how they're going to get out of this really big scandal."