The Norwegian princess Märtha Louise and her husband, the American businessman Durek Verrett, are suing several former members of their inner circle for defamation over what they described as a “calculated betrayal of trust”.

Court documents filed in Los Angeles on 14 September claim the former friends and colleagues took “private access once afforded to them and weaponised it”. The accused include “former intimate partners, trusted business associates, a family member”.

The documents allege that information including “confidential communications, disputed accusations and claimed insider knowledge” was used against Märtha Louise, Verrett and his company, Ohana, in what the couple describe as a “coordinated series of devastating public attacks”.

The compensation claims total in excess of $80m, the newspaper VG reports.

The legal action comes during a particularly challenging period for the Norwegian royal family. King Harald died in August aged 89, to be succeeded by his son Haakon, who is Märtha Louise’s brother. Harald’s sister, Princess Astrid, died aged 94, two days after attending his funeral in September.

At the same time, the royal family has been embroiled in several scandals including revelations about the Queen Mette-Marit’s friendship with Jeffrey Epstein. Her son Marius Borg Høiby was found guilty of two counts of rape in June. The queen, who has pulmonary fibrosis, underwent a lung transplant in the same month.

Märtha Louise and Verrett have been the subject of multiple headlines in recent years.

In 2023, before marrying Verrett, who describes himself as a sixth-generation shaman, the princess renounced her royal duties to focus on the couple’s alternative medicine business. Last year they starred in a Netflix documentary about their lives, Rebel Royals: An Unlikely Love Story.

The papers, filed to Los Angeles county superior court, state that the case was prompted by a “calculated betrayal of trust” and mentions the “recent loss” of the late king. The alleged “incessant misconduct” was said to have started years ago, but “continued and escalated” in 2025 and 2026.

“During that period, plaintiffs experienced significant medical and personal circumstances, including Verrett’s serious kidney failure, dialysis treatment, health deterioration and recent kidney transplant, as well as Princess Märtha Louise’s recent loss of her father,” the papers state.

“Although plaintiffs would ordinarily have preferred to devote this period to their health, family, grief, and recovery, the timing of this filing is governed by applicable legal deadlines. Plaintiffs must proceed at this unfortunate time to preserve their claims and protect their rights arising from defendants’ publications and conduct in 2025 and 2026.”

The lawsuit says the accused people, “far from being distant critics reporting from the outside”, were “at one time in the inner circle of Verrett and Princess Märtha Louise”. It adds: “They had been welcomed into Verrett’s private life, family relationships, communications, client-related affairs and business operations through relationships of intimacy, trust, confidence, and professional responsibility.”

The couple’s US lawyer Richard Roth told VG: “Our clients’ reputations have been judged by the public for years. Now the facts will be tested in a court of law.”

Court documents list two future hearings for the case in December.

The palace and representatives of the couple have been contacted by the Guardian for comment.