The Case That Shook the Profession

Few cases in recent legal history have generated as much anxiety across law firms as Mazur. What began as an unpaid fees dispute has become the most consequential judgement for legal services in a generation – and its costs implications are still working their way through the profession. This has led to what many practitioners are now referring to as Mazur conduct of litigation costs issues, particularly in relation to how work is delegated and recorded.

The original dispute arose when Charles Russell Speechlys LLP (CRS) sought to recover unpaid fees of over £50,000 from their former clients, Mrs Mazur and Mr Stuart. CRS instructed a second firm, Goldsmith Bowers Solicitors (GBS), to pursue the claim. Proceedings were issued, and the particulars of the claim were signed by GBS’s Head of Commercial Litigation – who, it emerged, did not hold a current practising certificate and had been indefinitely suspended from practice.

Mrs Mazur and Mr Stuart challenged the proceedings on the basis that the litigation had been conducted by an unauthorised person. The challenge ultimately reached the High Court – and the judgment that followed sent shockwaves through the entire profession.

The High Court Ruling That Changed Everything

In Mazur & Anor v Charles Russel Speechlys LLP [2025] EWHC 2341 (KB), Mr Justice Sheldon held that an unauthorised person was not entitled to conduct litigation, even under the supervision of a qualified solicitor. The High Court distinguished between supporting an authorised individual in conducting litigation, which was permissible, and conducting litigation under the supervision of an authorised individual, which was not.

The practical consequences were immediate and alarming. The decision conflicted with the typical operating model in which routine litigation work is delegated to paralegals, trainees, and other unauthorised persons in the interests of cost efficiency. Law firms, law centres, local authorities, and personal injury practices all faced the prospect that work carried out by their paralegals, legal executives, and trainee solicitors might amount to an unlawful reserved activity under the Legal Services Act 2007.

From a costs perspective, the implications were serious, giving rise to a wave of Mazur conduct of litigation costs challenges in detailed assessment proceedings. Paying parties began raising Mazur issues in points of dispute, challenging hourly rates for paralegals and legal executives, and arguing that costs for work done by non-authorised persons on reserved activities should be disallowed.

The Court of Appeal Judgement: March 2026

On 31 March 2026, the Court of Appeal handed down its landmark judgement in CILEX & Ors v Mazur & Ors [2026] EWCA Civ 369, overturning the High Court’s decision and providing crucial clarification on the meaning of “carrying on the conduct of litigation” under the Legal Services Act 2007.

The Court of Appeal – Vos MR, Briss C and Andrews LJ – unanimously overturned the High Court’s restrictive interpretation and restored the long-established principle that unauthorised staff may perform litigation tasks under appropriate supervision, without committing a criminal offence.

The Court of Appeal’s judgement restores a practical and workable interpretation of the Legal Services Act 2007, confirming that delegation within litigation teams is permitted – provided that an authorised lawyer retains ultimate responsibility and properly supervises the work being carried out.

For law firms and costs practitioners, this was broadly welcome news. The delegation model that most practices had operated for decades was restored. But the Court of Appeals’ judgement was not a simple return to the pre-Mazur position.

The Revised Judgement: May 2026

In May 2026, a revised version of the Court of Appeal judgement was issued. Certain paragraphs were amended in ways described as small but significant. These revisions have not yet made their way into the publicly available version of the judgment on the judiciary website, meaning many practitioners are working from an incomplete picture of the current legal position.

Solicitors and costs professionals should ensure they are working from the approach revised judgment rather than the version currently accessible via BAILII or the judiciary website. The amendments, though incremental, affect how certain passages of the judgment should be read and applied in practice.

Mazur Conduct of Litigation Costs: Why Challenges Are Still Being Raised

The Court of Appeal’s judgment resolves the fundamental question of whether supervised unauthorised persons can lawfully conduct litigation. It does not eliminate all costs and risks arising from Mazur, and practitioners should not treat it as a clean bill of health.

The question of whether supervision arrangements were adequate will remain live in costs disputes. These disputes are now commonly framed as Mazur conduct of litigation costs arguments, particularly where supervision and delegation are unclear.

Firms with poor supervision records face the prospect of having costs reduced or disallowed on the basis that delegation was not properly managed. Clients are already more alert to the question of who is actually doing the work on their case and whether that person is properly supervised.

In practical terms, paying parties can still raise the following challenges at detailed assessment:

1. Hourly rates for fee earners: Where work has been carried out by paralegals or other unauthorised fee earners, paying parties may argue that the rate claimed is not commensurate with the work done, or that the supervision arrangements were insufficient to justify the rate claimed.
2. Time entries and supervision: Vague or generic time entries that fail to identify who carried out the work, and whether adequate supervision was in place, remain vulnerable to challenge. The Court of Appeal confirmed that the authorised individual must retain responsibility for the work, and bills of costs should reflect that clearly.
3. Indemnity principle Where the retainer or fee arrangement does not accurately reflect the supervision model in place, paying parties may argue that the costs claimed exceed the client’s actual liability, engaging the indemnity principle.

What the Law Society and SRA Have Said

The Law Society updated its practice note following the Court of Appeal judgement, setting out its understanding of who is authorised to carry on the conduct of litigation under the Legal Services Act 2007 and what activities unauthorised team members can carry out on their own or under supervision.

The Law Society was clear that the judgment establishes a less restrictive framework than the High Court judgment, but it does not remove all limitations on what an unauthorised person employed by a regulated entity may do. The SRA is continuing to develop further guidance, and practitioners should monitor developments from both bodies as the post-Mazur landscape continues to settle.

Key Takeaways

• Mazur v Charles Russel Speechlys held that unauthorised persons could not conduct litigation even under supervision, causing widespread disruption across law firms.
• The Court of Appeal in CILEX v Mazur overturned that ruling, restoring the principle that delegation to unauthorised staff under proper supervision is lawful
• A revised version of the Court of Appeal judgement was issued in May 2026 with small but significant amendments – practitioners should ensure they are working from the correct version
• Cost challenges arising from Mazur are not eliminated by the Court of Appeal judgment – supervision adequacy, hourly rates, and time entry remain live issues at detailed assessment
• The Law Society and SRA are continuing to develop guidance – firms should keep their supervision and delegation arrangements under review

Frequently Asked Questions

What did the Court of Appeal decide in Mazur?

The Court of Appeal in CILEX v Mazur held that unauthorised persons – including paralegals, trainee solicitors, and legal executives – can lawfully conduct litigation tasks provided they do so under the supervision of an authorised individual who retains overall responsibility. This overturned the High Court’s ruling in Mazur v Charles Russel Speechlys.

What are the costs implications of the Mazur judgment?

The Court of Appeal’s decision restores the delegation model, but does not eliminate costs risk entirely. Paying parties can still challenge bills of costs on the basis of inadequate supervision, inappropriate hourly rates for the fee earner, vague time entries, and indemnity principle arguments where the retainer documentation does not accurately reflect how the work was carried out.

Is there a revised version of the Mazur Court of Appeal judgment?

Yes. A revised version of the judgment was issued in May 2026, with certain paragraphs amended in ways described as small but significant. The amendments do not appear to have made their way into the publicly available version on the judiciary website. Practitioners should ensure they are working from the approved revised judgment.

What should solicitors do following the Mazur Judgement?

Solicitors should review their supervision and delegation arrangements to ensure they are consistent with the Court of Appeal’s guidance. Bills of costs should clearly reflect who carried out each piece of work and confirm that appropriate supervision was in place. Time entries should be sufficiently detailed to withstand scrutiny at a detailed assessment.

Speak to Greener Costs Today

The Mazur judgement has changed the landscape for litigation costs recovery, with Mazur conduct of litigation costs issues continuing to shape how firms approach billing, supervision, and risk. Whether you need advice on how to structure your bills of costs in light of Mazur, support responding to points of dispute raising supervision or fee earner arguments, or strategic guidance on costs recovery in delegated litigation models, Greener Costs is here to help.

Our specialist costs lawyers work with solicitors and law firms across England and Wales, providing practical, up-to-date advice on all aspects of costs recovery and detailed assessment.

Get in touch today on 01204 263047 or email info@greenercosts.co.uk to speak with one of our team.