In Mazur v Charles Russell Speechlys LLP [2025] EWHC 2341 (KB), the High Court’s strict construction of what counts as the “conduct of litigation” has encouraged paying parties to allege that bills of costs are tainted by illegality where unqualified staff performed work. Some defendants now seek strikeout or wholesale disallowance of costs on that basis. These challenges remain largely untested, though they already surface on summary assessment. The field for attack may be narrow: pre-issue settlements involve non-contentious business; fixed-costs cases are unaffected; and in others, proof of who did what, and whether sanctions apply, will prove a formidable evidential hurdle.
In the aftermath of the decision in Mazur v Charles Russell Speechlys LLP [2025] EWHC 2341 (KB) paying parties have started making allegations in Points of Dispute, that either bills of costs should be struck out in their entirety, or the costs claimed in the Bill, should be disallowed on a wholesale basis, because the litigation has been conducted illegally by unqualified fee earners.
This was a foreseeable development, given the tenor of the decision in Mazur, and its emphasis on strictly defining the conduct of litigation, with no apparent scope for the delegated-but-under-supervision business model practised by many firms.
There will be some time yet before the allegations are tested in the crucible of detailed assessment, but this is already a concern on summary assessment.
It may be that the scope for such challenges is yet limited in three particular ways.
First, any case that is settled without the issue of proceedings, could be regarded as non contentious business, and therefore not litigation, and therefore the decision in Mazur simply has no application.
Secondly, in any case involving fixed costs, those costs are awarded whether the case is conducted by the firm’s Senior Partner, or the office cat, and irrespective of whether there is an enforceable conditional fee agreement or not.
Costs belong to the client. It might be thought to be a stretch that fixed costs cases should be troubled by Mazur.
Thirdly, there are then the questions of proof, of who did what and why, and which side of the line, the work done on the case falls into, before even getting into the arguments, as to whether a sanction of strikeout or disallowance is required or permissible on the law.