Mazur in the Court of Appeal: conduct of litigation and costs recovery

Mazur began as a fee dispute. The clients complained that their litigation had been run by an employee of a firm who did not hold a practising certificate or other authorisation to conduct litigation. In September 2025 Sheldon J, in the King’s Bench Division ([2025] EWHC 2341 (KB)), held that an unauthorised person was not entitled to conduct litigation simply because they were employed by, and supervised within, an authorised firm. The decision caused immediate concern across firms that rely on paralegals, trainees and other team members to progress claims.

CILEX appealed, with the Solicitors Regulation Authority, the Law Society, the Legal Services Board, the Law Centres Network and the Association of Personal Injury Lawyers all involved. The appeal was heard in February 2026 before the Master of the Rolls, the Chancellor of the High Court and Andrews LJ, with judgment handed down on 31 March 2026.

The court did not change the core rule: the conduct of litigation is a reserved legal activity under the Legal Services Act 2007, and only authorised or exempt persons may carry it on. What changed was the framework for delegation. As the Law Society summarised it, an authorised person can delegate tasks within the litigation to an unauthorised person, provided the authorised person maintains responsibility for those tasks, meaning formal responsibility for the task and responsibility for adhering to the professional principles.

In practice, the question is less about job titles and more about whether a properly authorised individual genuinely held the conduct of the matter. Regulators have said further guidance will follow, so firms should keep their supervision policies under review rather than treating the judgment as the last word.

Paying parties have used the Mazur litigation to question whether work by unauthorised staff is recoverable at all. After the Court of Appeal decision, a blanket objection to all paralegal time is harder to sustain. However, a targeted challenge may still succeed where the papers suggest that nobody authorised was truly responsible for the steps taken, or where significant decisions appear to have been made without oversight.

For receiving parties preparing a bill of costs, the practical answer is evidence. Keep a clear record of who held conduct, the supervision structure, and who approved key steps such as issuing proceedings, signing statements of truth and accepting offers. Points of dispute that raise the issue in general terms can then be answered with specific information in the replies, rather than broad assertion.

In solicitor and own client disputes, clients may also raise the point when they challenge a solicitor’s bill. The underlying question remains whether the charges are reasonable and properly payable under the retainer, but a firm that cannot show proper supervision may find the argument harder to resolve.

Review case management records to confirm that each matter names an authorised person with conduct. Make delegation and sign-off visible on the file. Check that time entries and the narrative in any bill describe the work accurately and identify who supervised it. When instructing a Costs Lawyer, provide this information early so it can be reflected in the bill and in any replies to points of dispute.

This article summarises reported judgments for general information in England and Wales. Read the full judgment and any later guidance or appeals before relying on it in a particular matter.