Business Interruption Expert Reports & CPR Part 35 Compliance
A CPR Part 35 expert report is the primary vehicle through which a business interruption expert’s opinions are placed before the English and Wales courts - a structured document governed by CPR Part 35, Practice Direction 35, and the overriding objective, not an informal loss calculation memo. Judges expect clarity on assumptions, data limitations, and the expert’s duty to the court rather than to the retaining party.
Core components of a CPR Part 35 compliant BI report
Reports should identify instructions, materials reviewed, qualifications, and the factual basis for each opinion. For BI quantum, that includes explicit definition of standard turnover, ROGP derivation, ICW testing, indemnity period boundaries, and reconciliation to trial bundles.
Visual aids - time-series charts, waterfall bridges, and formula walkthroughs - improve comprehension but must faithfully reflect underlying spreadsheets disclosed in concurrent evidence.
Ikarian Reefer duties in financial expert work
The Ikarian Reefer line of authority requires independence, objectivity, and fair exposition of rival methodologies where legitimate debate exists. In BI cases, that may mean presenting insurer-friendly and policyholder-friendly sensitivities on growth rates, or explaining why a particular seasonality adjustment is debatable within professional practice.
Experts should avoid partisan language, ad hominem commentary on opposing counsel, or vouching for the honesty of witnesses - those missteps invite satellite applications and undermine credibility.
Single joint experts vs party-appointed experts
Courts sometimes appoint a Single Joint Expert (SJE) on discrete technical issues, but high-value BI quantum disputes more commonly feature party-appointed experts followed by a joint statement under CPR PD35. The joint statement should isolate numerical disagreements, identify shared datasets, and flag any data requests still outstanding.
Practical checklist before exchange
Confirm the expert has reviewed pleadings, key correspondence on coverage positions, and the insured’s accounting policies. Ensure appendices include workpaper references that enable efficient hot-tubbing at trial.
Related Case Types
Deep-dive overviews with FAQs and structured data for common dispute patterns linked to this guide.
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