The magazine published topless photos of the Duchess of Cambridge in 2012, the magazine's lawyer told the UK Press Association on Tuesday.
The trial began Tuesday in France for six people associated with Closer magazine and regional newspaper La Provence, the Press Association reported. The French magazine Closer is separate from the UK's Closer magazine.
The images showed the duchess sunbathing topless while on holiday in the South of France in 2012 in the couple's private villa. They scandalized St. James Palace and dredged up memories of the royal family's rocky relationship with the media 15 years after the death of William's mother, Princess Diana, as she fled photographers in Paris.
"The incident is reminiscent of the worst excesses of the press and paparazzi during the life of Diana, Princess of Wales, and all the more upsetting to The Duke and Duchess for being so," a palace spokesman said in 2012.
According to the Press Association, Ernesto Mauri, chief executive of the publishing group that produces Closer, faces one charge of using a document obtained by a breach of privacy, along with Marc Auburtin, La Provence's publishing director at the time. Laurence Pieau, editor of Closer magazine, is charged with complicity. Agency photographers Cyril Moreau and Dominique Jacovides and Valerie Suau, who was a photographer for La Provence, face charges of invasion of privacy and complicity.
Jacovides and Suau deny taking photographs that were allegedly sold to Closer, the Press Association reported. Suau, who is accused of taking photographs that ran in La Provence, told the court she did not intend to breach the royals' privacy.
Paul-Albert Iweins, representing Closer magazine, argued that the photos cast the royal couple "in a positive light" and did not constitute a breach of privacy, the Press Association said.
Prince William said the decision to publish topless photographs of his wife was "particularly shocking" given his late mother's battles with the paparazzi.
The couple's lawyer, Jean Veil, read a declaration in court Tuesday on William's behalf.
"In September 2012, my wife and I thought that we could go to France for a few days in a secluded villa owned by a member of my family, and thus enjoy our privacy... The clandestine way in which these photographs were taken was particularly shocking to us as it breached our privacy."
A French court fined Closer in 2012 for printing the images and banned it from the distributing the magazine in print or online.
Judge Florence Lasserre-Jeannin will announce the verdict in this trial on July 4, the Press Association said.