It comes after Meghan won a privacy action against the Mail on Sunday earlier this year after it printed parts of the letter she sent to her father.
While she won much of her claim without needing a trial, judge Mark Warby had said the issue of who owned copyright to the letter still needed to be decided.
It was due to the argument that the letter was co-authored by Jason Knauf, former communications secretary to the Sussexes, implying that its copyright belonged to the Crown.
Now, Jason has denied being a co-author, and “the Keeper of the Privy Purse acting on behalf of Her Majesty The Queen ... did not consider the Crown to be the copyright owner (whether in part or sole) of the Electronic Draft”.
Representing Meghan, Ian Mill, QC, told the court: “This unequivocal statement of Mr Knauf’s position also gives the lie to the defendant’s inferential case, in its defence to both the privacy and copyright claims, that the claimant considered using the letter ‘as part of a media strategy."
With this, the judge granted summary judgement, meaning a final judgement in Meghan's favour that avoids a trial.
The publication was also ordered to pay 90 percent of the costs incurred by Meghan for the Summary Judgement Application in her legal battle, after a judgement was ruled in early March.
Now, the judge has added to this by ordering the Mail on Sunday to pay the remaining 10% of Meghan's court costs.