CILEX v Mazur: Court of Appeal reasserts delegation model for conduct of litigation

In CILEX v Mazur [2026] EWCA Civ 369 (handed down 31 March 2026) the Court of Appeal overturned Mr Justice Sheldon's much-debated High Court decision ([2025] EWHC 2341 (KB)) and clarified and re‑affirmed the orthodox understanding of how civil litigation may lawfully be carried out by teams of individuals. For most commercial litigation practices the decision is reassuring rather than disruptive. Its real significance lies in the precision with which the Court has framed the supervisory responsibility that authorised individuals must exercise.

Background of CILEX v Mazur

The case began as an ordinary fee-recovery claim. Charles Russell Speechlys instructed Goldsmith Bowers Solicitors (GBS) to recover £54,263.50 in unpaid fees from Mrs Mazur and Mr Stuart. The Particulars of Claim were signed by Peter Middleton, GBS's 'Head of Commercial Litigation' – a former solicitor who had been indefinitely suspended from practice in 2008. The evidence showed that Mr Middleton had also taken instructions, advised, drafted the claim form, served statements of case and instructed counsel.

Mrs Mazur and Mr Stuart, acting in person, challenged his right to carry out those functions lawfully. Sheldon J held in September 2025 that an employee of an authorised firm of solicitors cannot conduct litigation merely by virtue of employment, even when supervised. Long-settled working arrangements across the profession, in particular those which involved legal executives and paralegals operating under the supervision of solicitors were suddenly in question. CILEX, supported by APIL and the Law Centres Network, was granted an expedited appeal heard before the Master of the Rolls in February 2026.

The legislative framework

The relevant legislation is the Legal Services Act 2007 (the LSA). The LSA designates certain 'reserved legal activities' that may only be carried out by, or under the authority of, an 'authorised person'. In this context an authorised person is a solicitor or a legal executive holding a specific qualification allowing them to conduct litigation. The conduct of litigation is designated as a reserved legal activity under s.12 of the LSA and Schedule 2.

Section 13 of the LSA provides that the question whether a person is entitled to carry on a reserved legal activity is to be determined solely in accordance with the LSA.

Section 14 of the LSA makes it a criminal offence for any person to 'carry on' a reserved legal activity unless they are entitled to do so.

Section 1(3) sets out the ‘professional principles’ – including independence and integrity, proper standards of work, acting in the best interests of clients, and duties owed to the court – compliance with which rests on authorised persons.

The question for the Court of Appeal was whether an unauthorised employee of an authorised firm, performing tasks falling within the conduct of litigation under the supervision of an authorised individual, is 'carrying on' the reserved activity within the meaning of s.14 and so committing an offence.

What the Court of Appeal decided on 'conduct of litigation'

Giving the leading judgment (with which Vos MR and Andrews LJ agreed), Birss LJ rejected Sheldon J's binary distinction between 'supporting' an authorised solicitor and 'conducting' litigation under supervision. The appeal court drew a sharp distinction between two phrases in the LSA that the High Court had treated as interchangeable. 'Conduct of litigation’ describes the nature of the activities, whereas ‘carrying on’ a reserved legal activity refers to the assumption of responsibility for, and control over, those activities (Birss LJ at [187]). The s.14 offence attaches to the latter, not the former.

The result is that an unauthorised person may lawfully perform any task within the conduct of litigation for and on behalf of an authorised individual. Where the authorised individual retains formal responsibility for the task and responsibility for ensuring compliance with the s.1(3) professional principles, and puts in place appropriate arrangements for supervision, it is the authorised individual – not the unauthorised person — who is 'carrying on' the conduct of litigation. The unauthorised person commits no offence.

How supervision is structured is primarily a regulatory question for the SRA and CILEX Regulation, although the boundary between lawful delegation and impermissible delegation remains fact‑sensitive. The Court signalled that the appropriate level of supervision will depend on the circumstances: high-stakes work may require specific approval from an authorised person, more routine work could be carried out by the unauthorised person without review and approval of each element by an authorised person, but the authorised person might hold regular meetings with the unauthorised person and carry out sampling of their work.

The Court declined to provide an exhaustive definition of what constitutes the conduct of litigation. At [193] it identified seven categories of activity (drawn from a Law Society list, treated as common ground) that are unlikely to fall within the definition – pre-litigation work; advice in connection with proceedings; correspondence with the opposing party; gathering evidence; instructing experts and counsel; signing statements of truth; and signing other documents the CPR permits a legal representative to sign. The Court stressed that whether particular acts fall within the conduct of litigation is context‑dependent. Several of these activities may form part of the reserved activity where, in substance, they involve the exercise of procedural control or responsibility for the litigation. The list is not a safe harbour and should not be read as determinative.

Andrews LJ's concurring judgment at [198] adds an important note. The essential question in any disputed case will be whether the unauthorised person is, in truth, acting on behalf of the authorised individual. Genuine delegation under genuine supervision is lawful; nominal supervision is not.

The Law Society confirmed on 24 April 2026 that it would not appeal the Court of Appeal's judgment.

What Mazur means for delegation and supervision in litigation

For most City litigation practices, nothing operational needs to change. The team-based delivery of complex commercial disputes – partner-led, with associates, trainees and paralegals performing significant portions of the procedural work – is a model the Court of Appeal has confirmed remains lawful.

The practical takeaway is evidential rather than structural. Responsibility must remain traceable to a named authorised individual and supervisory arrangements must be capable of being shown to satisfy that responsibility if scrutinised. The Law Society’s new practice note (13 April 2026) indicates that future practice should include written details of the authorised individual responsible for each matter, together with a clear record of any delegated instructions given by that authorised individual to non‑authorised staff, covering key decisions and formal steps in the proceedings. Updated SRA guidance on effective supervision is awaited.

The decision does not legitimise the unsupervised conduct of litigation by suspended or struck‑off solicitors. The lawfulness of delegation depends on genuine supervision and the authorised individual’s assumption of responsibility. Nominal or cosmetic supervision will not suffice.

Firms whose supervision is robust in substance but informal in record-keeping should review their arrangements with that in mind.

The same analysis applies to in‑house legal teams that themselves retain the conduct of litigation, for example in debt recovery, employment, regulatory enforcement or contentious tax matters. Where an in‑house function includes non‑authorised staff — such as legal apprentices, paralegals, trainees, costs officers or foreign‑qualified lawyers without English practice rights – Mazur emphasises that responsibility must remain with a named authorised individual, supported by genuine and effective supervision.

For General Counsel and Heads of Legal, the practical focus should be on three points:

• first, identifying who within the team is formally authorised to conduct litigation in England and Wales;
• second, ensuring that responsibility for each live matter is clearly allocated to, and recorded against, a named authorised person; and
• third, confirming that delegation to non‑authorised staff and the supervision of their work is sufficiently documented to withstand scrutiny by a regulator, an opponent or a costs judge if required.

Responsibility for the conduct of litigation

CILEX v Mazur restores orthodoxy – but with greater clarity and precision. Litigation can continue to be delivered through teams, and the day‑to‑day tasks of litigation may properly be delegated. What the Court of Appeal has re‑emphasised, however, is that responsibility for 'carrying on' the conduct of litigation remains, as it has in long‑established professional practice, with the authorised lawyer who directs the case. For sophisticated users of litigation services, and for in-house teams that themselves retain the conduct of litigation, the message is one of reassurance coupled with a clear instruction: current ways of working are not disrupted, but supervision must now be consciously structured and capable of being evidenced.

This publication is a general summary of the law. It should not replace legal advice tailored to your specific circumstances.

© Farrer & Co LLP, April 2026