The Defendant here being the newspaper, while the claimant is the person suing the paper.

On the issue of costs, it should equally be open to a claimant to rely on failure by a newspaper to subscribe to the regulator thereby depriving him or her of access to a fair, fast and inexpensive arbitration service. Where that is the case, in the exercise of its discretion, the court could take the view that, even where the defendant is successful, absent unreasonable or vexatious conduct on the part of the claimant, it would be inappropriate for the claimant to be expected to pay the costs incurred in defending the action.

5.6 At one extreme, when the court concluded that it was entirely reasonable for a claimant (although unsuccessful) to bring the claim, it might be possible for the court to go further and order that the claimant’s costs should be met by the defendant: the justification would be that although the claimant has not been successful, by not being a member of an industry regulator, the defendant had forced the claimant to use the expensive court system whereas an effective arbitral mechanism could have resolved the issue without the expenditure on costs at all.53

ALSO see Part J, Chapter 3, Para 6.8, on page 1514

if a publisher did not join the regulator, with the result that the specialist arbitral system was not available to a claimant wishing to pursue a remedy (particularly if of limited means and, thus, unable otherwise to obtain access to justice), I see no reason why the court should not be able to deprive even the successful publisher of costs that would not have been incurred had the alternative arbitration been available. I go further and suggest that, in a case legitimately brought and potentially borderline, the court would even retain the discretion to order the successful publisher to meet the costs of an unsuccessful claimant (although I recognise that this would not be the case if the court was dealing with vexatious or utterly misconceived litigation). Ultimately, the discretion of the court would govern all these issues, but I see only advantage in supporting an arbitral system that could be seen to have been independently set up and operated by a regulator, albeit itself set up by the press but managed and run independently of it.