News Analysis: Prince Harry Puts Britain’s Press on Trial

Many of the journalists who used those methods are still employed by The Mirror, and some have risen to positions of authority in the company, Mr. Sherborne said. “The notion that this took place years ago is misplaced,” he said.

Still, that is the nub of the case made by the Mirror Group’s lawyers. Because the bulk of this activity took place between 1991 and 2011, the lawyers said in a filing, it lies well beyond the six-year time limitation that generally applies to legal complaints of privacy violations. The practice of phone hacking has all but vanished since the scandal erupted in 2011, according to lawyers who specialize in these cases.

Lawyers for Harry and three other plaintiffs in the case counter that the company concealed its illegal activity from them, so they could not reasonably have been expected to discover it sooner. In addition to Harry, the others are Nikki Sanderson and Michael Taylor, who both appeared in the popular TV series “Coronation Street,” and Fiona Wightman, the former wife of a well-known comedian, Paul Whitehouse.

Daniel Taylor, a lawyer whose firm, Taylor Hampton, represents Ms. Wightman, said it was extraordinary that the trial was going ahead at all. It is only the second such case to go to trial after dozens of cases, and more than decade of hacking-related litigation, he said, and it poses risks to both sides.

Harry, he said, “is likely to be subjected to rigorous and sustained cross-examination” by lawyers representing Mirror Group. That could prove embarrassing, given that the hacking took place during the years before Harry met his wife, Meghan, when he was single and involved in sometimes turbulent relationships.

But the Mirror Group is also taking a risk in going to trial, Mr. Taylor said, since a defeat could encourage other victims of hacking to come forward. “It is willing to do so because a win or partial success at trial will, in its view, slow or stop the oncoming tide of claims being brought against the company,” he said.

On Monday, Harry managed to irritate the judge, Timothy Fancourt, by not showing up for the trial as expected. Mr. Sherborne explained that he had stayed in California on Sunday to celebrate the second birthday of his daughter, Lilibet, and would be in court to testify on Tuesday and Wednesday. A lawyer for the Mirror Group expressed concern that he would not get a full day and a half for cross-examination.