This guide covers preliminary assessment, essential contents of the instruction, document packs, fee agreements, Part 35 duties, and joint instruction of a single joint expert.
Preliminary Review and Early Instruction
A preliminary review, sometimes called a quantum screening, allows the solicitor to assess whether expert evidence is justified, what documents exist, and the approximate range of loss before issuing proceedings. The dispute accountant reviews key contracts and accounts under litigation privilege and advises on: viability of the quantum claim; further disclosure needed; appropriate measure of damages; and whether investigation or valuation is required.
Early instruction supports without-prejudice negotiation, litigation hold on accounting systems, and mitigation advice. It also avoids instructing the wrong specialist, for example, a valuer where forensic investigation is needed first.
Essential Contents of the Letter of Instruction
Every letter of instruction should include: parties and proceedings reference; the expert's defined role (CPR Part 35 expert, adviser, or determiner); background facts agreed and in dispute; legal framework and measure of damages; specific questions for the expert; documents provided and anticipated further disclosure; timetable and hearing date; fee basis; and confirmation of the expert's overriding duty to the court.
Avoid asking the expert to 'support the claimant's case.' CPR Part 35.3 requires independence. Questions should be neutral and precise, for example: 'What was the claimant's lost gross profit between [dates] but for the breach, and what assumptions underpin that figure?'
| Element | Purpose | | --- | --- | | Specific questions | Define scope and report structure | | Agreed/disputed facts | Focus analysis | | Legal framework | Align measure of damages | | Assumptions on liability | Alternative scenarios if needed | | Timetable | Manage court deadlines |
Documents to Provide
Core documents for commercial loss claims: contract and variations; correspondence on breach and mitigation; audited accounts (three years pre-breach); management accounts for the loss period; budgets and forecasts; invoices for wasted expenditure; and prior expert reports.
Shareholder disputes: Companies House filings, SHA, board minutes, dividend records. M&A: SPA, disclosure letter, completion accounts, due diligence files. Fraud: bank statements, general ledger, payroll, CRM exports. Construction: contract with amendments, programmes, EOT notices, cost ledgers.
Organise documents with an index; use a data room for large matters. Confirm litigation hold covers email, ERP, and cloud storage before the expert begins.
Fee Agreement and Timetable
Agree fees in writing before work starts: hourly rates by grade; estimated hours per phase; fixed fee for defined scope where appropriate; disbursements; payment terms; and procedure if scope expands. Contingency or success-based expert fees are impermissible, the expert must have no interest in the outcome.
Milestones might include: document review and request list (2 weeks); draft report (4–8 weeks); final report after comments; joint meeting; trial attendance. Urgent adjudication or injunction support requires agreed premium rates and availability.
CPR Part 35 and Single Joint Expert Instructions
Practice Direction 35 requires the expert report to contain: the expert's qualifications; material instructions; documents relied upon; factual assumptions; opinions and range of opinion; statement that the expert understands the duty to the court; and declaration of compliance.
For a single joint expert (SJE), both parties must agree the joint instruction, typically signed by both solicitors after circulating a draft. Agree: neutral questions; simultaneous document provision; fee sharing; procedure for supplemental questions; and dispute resolution on instruction disagreements (CPR 35.7 court application).
SJE instructions must not favour one party's formulation. Party-appointed experts remain common in high-value disputes where adversarial testing is required. The Ikarian Reefer [1993] principles, independence, transparency, and assistance to the tribunal, apply to all expert roles.