Single Joint Expert in Damages Cases: A Solicitor's Guide
A Single Joint Expert (SJE) provides one independent opinion on quantum, appointed jointly by the parties or directed by the court under CPR 35.7. SJE appointment can reduce costs and narrow issues - but requires careful management of the joint instruction process.
This guide explains when SJEs are appropriate in damages cases, how PI practice differs from commercial litigation, and the procedural steps for joint letters of instruction and written questions under CPR Part 35.
CPR 35.7 and the Court's Power to Direct an SJE
CPR 35.7 allows the court to direct that evidence on a particular issue is to be given by a Single Joint Expert selected by the court, agreed by the parties, or chosen from a list supplied by the parties. Practice Direction 35 emphasises that SJEs should be used where possible to save costs and promote settlement. The court will consider: whether the issue is within a recognised body of expertise; whether an SJE is proportionate to claim value; and whether the parties can agree instructions. Either party may apply for SJE appointment, or the court may raise it of its own motion at the CMC. Opposition requires good reason - disproportionate complexity or fundamental disagreement on instruction scope.
When an SJE Is Appropriate in Damages Cases
SJE appointment works well for: straightforward loss of earnings claims with clear employment records; fatal accident dependency calculations; employment tribunal loss of earnings; and lower-value PI claims where both parties want to avoid duplicate expert costs. SJE is less suitable for: high-value clinical negligence with multiple interacting heads; complex commercial but-for disputes where each party needs independent analysis; international arbitration (where party-appointed experts are the norm); and cases where the parties' instructions would fundamentally differ on assumptions. Solicitors should assess whether a joint instruction is achievable before agreeing or applying for SJE appointment.
PI vs Commercial SJE Practice
In personal injury, SJEs are routinely directed for loss of earnings and pension loss in multi-track claims where quantum is not heavily contested. The APIL-accredited forensic accountant is the typical SJE profile. In commercial litigation, party-appointed experts are the default in High Court disputes - SJEs are rare except for discrete valuation issues (e.g. a property valuation point). Family financial remedy proceedings use SJE directions under FPR Part 25 for business valuations. Employment Tribunal cases may use jointly instructed experts by agreement without formal CPR 35.7 direction. Match the expert type to the practice area: a commercial forensic accountant for contract loss, not a PI specialist without commercial experience.
The Joint Letter of Instruction
Both parties must agree the letter of instruction to the SJE - or the court will determine disputed terms. The joint letter should: identify the issues for the expert; set out agreed facts and disputed facts; specify the legal framework (without asking the expert to advise on law); list documents to be provided; state the timetable; and address fee arrangements (typically split equally unless the court orders otherwise). Disputes on instruction scope should be resolved before the expert begins work - an expert receiving contradictory instructions from each party cannot fulfil their CPR Part 35 duties. Solicitors should negotiate the joint letter as carefully as they would a Part 36 offer.
Written Questions and Challenging the SJE Report
Under CPR 35.6, parties may put written questions to the SJE once - for clarification, and in some circumstances to challenge methodology. Questions must be proportionate and not a fishing exercise. The SJE's answers are part of their evidence. Where a party fundamentally disagrees with the SJE's conclusions, they may apply for permission to adduce their own expert evidence under CPR 35.7(4) - but permission is not granted lightly where an SJE was directed. Cross-examination at trial remains available. For damages SJEs, focus questions on: multiplicand assumptions, retirement age, discount rate application, and care hour inputs - the typical pressure points in PI quantum.
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