The Duchess of Sussex was accused of compromising the privacy of her own friends by supplying their names in a legal document that she wants to remain secret, the High Court heard on Wednesday.
The duchess "freely" and "without being compelled" disclosed the identities of five friends whose privacy she now fears will be breached.
Meghan gave the names in a confidential document to Associated Newspapers, the publisher of the Mail on Sunday, who she is suing for breach of privacy and copyright over its publication of a handwritten letter to her father, Thomas Markle.
In legal submissions, the duchess has warned that being forced to identify the friends "is an unacceptable price to pay" in pursuit of her legal claim. She is arguing that naming them would breach their privacy under the European Convention on Human Rights, while the newspaper argues that they must be disclosed as a key principle of "open justice".
At one stage in Wednesday's court proceedings, Meghan's barrister accidentally let slip the surname of one of the friends his client is seeking to keep anonymous. Mr Justice Warby, the judge, suggested such an error was "bound to happen" before immediately ordering that the name should not be reported.
It also emerged that only one of the friends – Friend B, an American citizen who says she approached People magazine of her own accord – has given a witness statement. A barrister for the newspaper group said the statement "has been shown to be unsatisfactory", but did not go into any further detail.
It was disclosed that the duchess agreed to pay in full $132,220 (£67,888) in costs to Associated Newspapers after the publisher successfully argued that elements of her case be struck out. The costs are just a fraction of a multi-million legal bill expected should the case go to a full trial next year.
The five friends – who can be identified only by the initials A to E – gave briefings to People magazine, a US publication, last February, at a time when Meghan was "heavily pregnant", "vulnerable" and being subjected to bullying by parts of the media.
The People magazine article revealed the existence of the letter to her father which was subsequently published in the Mail on Sunday, prompting the ongoing High Court action.
In legal submissions, her lawyers said: "Forcing the claimant [the duchess], as the defendant urges the court to do, to disclose their identities to the public at this stage is an unacceptable price to pay for the right to pursue her claim for invasion of privacy against the defendant."
Her barrister, Justin Rushbrooke QC, told the court that Associated Newspapers' case is that Meghan had "compromised" her friends' right to privacy "by putting their names into a public court document". He added: "We say, on any analysis, that is actually a grotesque perversion of what's actually happened."
Rushbrooke said the duchess had been forced to identify her friends in a legal request by Associated Newspapers and added that the five were entitled to "a very high level of super-charged right of confidentiality".
He went on: "The friends are not parties to this action, but unwilling participants. At this early stage of the litigation, it cannot be said with certainty that they would be witnesses at the trial."
Antony White QC, representing Associated Newspapers, told the court: "The five individuals have already been identified, not under compulsion but as part of the response to the request for further information. The question is not should their identities be disclosed – that has happened – it is should they be anonymised in these proceedings?
"There is no proper evidential basis [for the application]. There is no evidence at all from four of the five friends, and the evidence from the fifth [Friend B] has been shown to be unsatisfactory."
Friend B's statement has not been made public but, in legal submissions, Associated Newspapers' lawyers said: "There is only some generic speculation by the claimant's solicitor as to the possible effect of the publication of the names, and a witness statement from Ms B, the contents of which are questionable and misleading."
Justice Warby reserved judgment and said he hoped to make a ruling on the friends' anonymity by mid-August.
Meghan Markle pays $130,000 in legal costs
The Duchess of Sussex has paid almost $132,452 (£68,000) in legal costs to Associated Newspapers, the publisher she is suing for breach of privacy.
The legal bill, totalling $132,264 (£67,888), arose after Mr Justice Warby, the judge in the case, struck out parts of her claim as irrelevant.
Meghan's lawyers had wanted to argue in court that The Mail on Sunday had acted dishonestly, "stirred up" issues with her father and had an "agenda" against her.
But in a judgment in May, Mr Justice Warby struck out those claims, and Associated pursued the duchess over the costs of the hearing. In legal documents released on Wednesday, the High Court was told that "following written submissions by both parties, on July 22 2020 the claimant agreed to pay the defendant's costs in full".
With her own legal bill on top, the strike out hearing, which took a day in court, will have cost the Duchess at least $194,849 (£100,000). Should the case go to full trial next year, as it is expected to do, costs are likely to spiral into the millions.