Prince Harry was a no-show for his trial against U.K. publisher The Mirror on Monday – leaving the judge frustrated.

The royal’s lawyer said the Duke of Sussex would be unavailable to testify following opening statements because the 38-year-old had taken a flight from Los Angeles after the birthday of his 2-year-old daughter, Princess Lilibet, on Sunday.

The prince resides in Montecito, California, with his wife Meghan Markle and their two children.

"I’m a little surprised," said Justice Timothy Fancourt, noting he had directed Harry to be present for the first day of his case.

PRINCESS LILIBET TURNS 2: PRINCE HARRY AND MEGHAN MARKLE'S DAUGHTER CELEBRATES BIRTHDAY AWAY FROM ROYAL FAMILY

A close-up of Prince Harry in a grey suit

Prince Harry was a no-show on the first day of his court showdown with a British tabloid publisher. (Max Mumby/Indigo)

Mirror Group Newspaper’s lawyer, Andrew Green, said he was "deeply troubled" by the prince’s absence on the trial’s opening day.

Harry had been scheduled to testify Tuesday, but his lawyer was told last week the duke should attend Monday’s proceedings in London’s High Court in case the opening statements concluded before the end of the day.

The case against Mirror Group is the first of the prince’s several lawsuits against the media to go to trial. It is one of three publishers he alleged unlawfully snooped on him for scoops on the royal family.

Harry’s lawyer, David Sherborne, said phone hacking and forms of unlawful information gathering were carried out on such a widespread scale, it was implausible the publisher’s newspapers used a private investigator to dig up dirt on the prince only once, which is what they have admitted.

Prince Harry smiles as he arrives in court.

Prince Harry skipped the first day of proceedings after celebrating the birthday of his daughter Lilibet. (Jordan Pettitt)

"The ends justify the means for the defendant," Sherborne said.

Stories about the youngest son of King Charles III and the late Princess Diana were big sellers for the newspapers, Sherborne said. He described how some 2,500 articles covered all facets of his life.

"There was no time in his life when he was safe from these activities," Sherborne said. "Nothing was sacrosanct or out of bounds."

Mirror Group claimed it used documents, public statements and sources to legally report on the prince. However, Sherborne said it was not hard to infer that Mirror journalists used the same techniques on Harry — eavesdropping on voicemails and hiring private eyes to snoop — as they did on others.

CLICK HERE TO SIGN UP FOR THE ENTERTAINMENT NEWSLETTER

Prince Harrys book Spare on display at a store

Prince Harry has spoken out about his distain towards the British press in his memoir "Spare." (Lev Radin/Pacific Press/LightRocket)

When he enters the witness box, Harry will be the first member of the British royal family in more than a century to testify in court. He is expected to describe how the media hounded him all throughout his life, as well as impacted his personal relationships. During the trial, Mirror Group's attorney will cross-examine Harry.

Harry has blamed ruthless paparazzi for causing the car crash that killed his mother in 1997. She was 36. He also said that harassment and intrusion by the U.K. press prompted him and his wife, a former American actress, to leave the country.

According to court documents, Harry said that ongoing tabloid reports made him wonder whom he could trust. He feared that friends and associates were betraying him by leaking private information. He said his circle of friends shrunk as he suffered "huge bouts of depression and paranoia." Relationships fell apart as the women in his life – and even their family members – were "dragged into the chaos."

Harry said that he later learned that the source was not disloyal friends, but rather aggressive journalists and private investigators they hired to eavesdrop on voicemails and track him.

Prince Harry in a blue suit waves for photos as he walks out with his new fiancée Meghan Markle, wearing white and putting her hand up in the air

The Duke and Duchess of Sussex reside in California with their son Prince Archie and daughter Princess Lilibet. (DANIEL LEAL/AFP)

Mirror Group Newspapers insisted it did not hack Harry’s phone. They argued their articles were based on legitimate reporting techniques.

The publisher admitted and apologized for hiring a private eye to dig up dirt on one of Harry’s nights out at a bar, but the resulting 2004 article headlined "Sex on the beach with Harry" is not among the 33 in question at trial.

Mirror Group has paid more than 100 million pounds ($125 million) to settle hundreds of unlawful information-gathering claims, and printed an apology to phone hacking victims in 2015. However, it denies executives – including Piers Morgan, who was editor of the Daily Mirror between 1995 and 2004 — knew about hacking.

Harry detailed his fury at the U.K. in his memoir "Spare," which was published in January of this year. The prince has also spoken out about his frustration in several televised interviews.

PRINCE HARRY, MEGHAN MARKLE 'NOWHERE NEAR DONE' TALKING ABOUT ROYALS, MIGHT MAKE ANOTHER DOCUMENTARY: EXPERT

Princess Diana wearing a hat

Prince Harry has blamed the paparazzi for the death of his mother Princess Diana. The Princess of Wales passed away in 1997 from injuries she sustained in a Paris car crash. She was 36. At the time, the royal was being chased by photographers. (Getty Images)

The opening statements mark the second phase of a trial in which Harry and three others have accused the Mirror of phone hacking and unlawful information gathering.

Sherborne also represents two actors from the soap opera "Coronation Street." He claimed unlawful acts were "widespread and habitual" at the Daily Mirror, Sunday Mirror and Sunday People, and carried out on "an industrial scale."

Two judges — including Fancourt — are in the process of deciding whether Harry’s two other phone hacking cases will proceed to trial.

Several other U.K. outlets have argued that the cases should be thrown out because Harry failed to file the lawsuits within a six-year deadline of discovering the alleged wrongdoing. Meanwhile, Harry's lawyer said he and other claimants should be granted an exception to the time limit because the publishers in questioned lied to hide their illegal actions.

The Duke and Duchess of Sussex stepped back as senior royals in 2020.

The Associated Press contributed to this report.