Three weeks after their crushing legal defeat at the hands of the Duchess of Sussex last month, the owners of the Mail on Sunday returned to court in characteristically belligerent form – and had another bad day.

Their application for permission to appeal against his judgments on privacy and copyright was firmly rejected. Having read a lengthy submission from Associated Newspapers and heard arguments from counsel, Lord Justice Warby dismissed the case in a few words, saying he ‘saw no prospect’ of any other court coming to a different conclusion.

The company can and probably will pursue the matter anyway, by appealing to the court of appeal against the judge’s decision to refuse it permission to appeal. Mail papers tend to exhaust legal options in this way as a matter of policy, no matter how often they lose and no matter what it costs them.

Associated applied the same dogged approach to almost all of the arguments at the four-hour online hearing in London, which addressed some issues left over after last month’s ruling. While the Duchess has resoundingly won her claim arising from publication by the Mail on Sunday of a private letter she had written to her father, matters such as costs and remedies remain unresolved, as do her claim about breach of data protection law and some technical legal issues relating to copyright.

Exactly what form of financial compensation the Duchess should receive will be a matter for another hearing in late April or May, but she won an important argument about her legal costs. Associated Newspapers said that since she had scored only a partial victory it should only have to pay 75 per cent of costs, but the judge said the figure should be 90 per cent – with the remainder still payable if she wins on the outstanding issues.

He also ordered an interim payment of £450,000. The total costs sum has yet to be fixed, but the Duchess is currently claiming £1.5m.

Associated has dug its heels in on several points that are likely to drag out proceedings without much obvious benefit to anyone. It rejected an offer by the Duchess’s counsel to drop the third and least significant element of her complaint, relating to breach of data protection rights. That will now go forward to be heard by Lord Justice Warby.

At the same time, the newspaper company still appears determined that there should be a trial in the autumn on the question of whether anyone besides the Duchess held any form of copyright in the letter at the heart of the case. This was the one element of the case on which the judge declared last month that he could not rule without hearing witness evidence, but given the rest of the judge’s findings it appears a marginal issue and it is hard to see what Associated hopes to gain.

It also emerged at the hearing that the Duchess is taking an unusual approach to compensation. Rather than seeking conventional damages (though it may come to that) she is asking for an ‘account of profits’, meaning that she wishes to secure from Associated a sum equivalent to the profits it made by breaching her rights.

Whether that might be allowed, and how that sum might be calculated, will be matters for further hearings. The Duchess of Sussex v Associated Newspapers Limited is set to drag on, and there will be a lot more court days, and a lot more legal costs, before it is concluded.

In the short term the most important of these is likely to see Associated arguing before the court of appeal that it should be allowed to appeal Lord Justice Warby’s judgment.

This post originally appeared on the Byline Investigates website and is reproduced with permission and thanks