Supplementary & Addendum
Expert Witness Reports
updated evidence for live cases
CPR-compliant updates to
expert witness evidence.
Our chambers prepares supplementary expert reports and addendum expert reports to address new evidence, evolving clinical presentations, or responses to Part 35 questions. These updates maintain compliance with CPR Part 35 and Practice Direction 35, ensuring the court receives timely, impartial revisions without prejudice to the expert’s overriding duty.
Instructions accepted by our chambers include deterioration in the claimant’s condition, newly disclosed records, or challenges raised by the opposing expert. Each addendum expert report is issued with a fresh declaration of truth and a clear audit trail of the changes, preserving transparency under CPR 35.3.
Three triggers for a
supplementary expert report.
New clinical evidence
Our chambers accepts instructions when the claimant’s condition deteriorates or improves post-report, requiring an updated expert witness report to reflect the revised prognosis, treatment needs, or causation analysis under CPR 35.12.
Part 35 questions
Members of our chambers respond to written questions from the opposing party under CPR 35.6, issuing a supplementary expert report that addresses each point transparently while maintaining the expert’s duty to the court.
Joint expert meetings
Following joint discussions under CPR 35.12, our experts prepare an addendum expert report to record areas of agreement, disagreement, and any revised opinions, ensuring the joint statement remains compliant with Practice Direction 35.
What an addendum expert report
must include.
Instruction & scope
The specific reason for the addendum expert report — new records, Part 35 questions, or clinical change — and the documents reviewed since the original report, listed with dates and sources under CPR 35.10.
Revised findings
Updated diagnostic conclusions, causation analysis, or prognosis, cross-referenced to the original report’s sections, with clear reasoning for any changes under CPR 35.3.
Response to questions
Where the addendum expert report addresses Part 35 questions, each question is quoted verbatim, followed by the expert’s response, ensuring compliance with CPR 35.6(2).
Joint statement updates
Where the supplementary expert report follows a joint discussion, the addendum records any changes to the joint statement, including areas of agreement or disagreement under CPR 35.12.
Declaration of truth
A fresh CPR Part 35 declaration, signed statement of truth, and confirmation of the expert’s continuing duty to the court, independent of the instructing party.
Audit trail
A schedule of changes from the original report, including page references, dates, and the rationale for each revision, ensuring transparency for the court.
Appendices
New records, test results, or correspondence referenced in the addendum expert report, appended in full to maintain compliance with CPR 35.10(2).
How we prepare a
supplementary expert report.
Our chambers ensures every addendum expert report is prepared with the same rigour as the original, maintaining compliance with CPR Part 35 and the Civil Justice Council’s 2014 Guidance. The methodology is documented to withstand scrutiny at trial.
-
01
Instruction review
We confirm the scope of the addendum expert report, including the specific trigger — new records, Part 35 questions, or clinical change — and the documents to be reviewed under CPR 35.10.
-
02
Original report analysis
Our experts re-examine the original report to identify sections requiring revision, ensuring consistency with the updated evidence and maintaining the expert’s duty to the court under CPR 35.3.
-
03
New evidence assessment
Where the supplementary expert report responds to new records or clinical changes, the expert conducts a fresh assessment, documenting any additional interviews or tests under Practice Direction 35.
-
04
Part 35 question response
Each question is addressed in turn, with the expert’s response clearly separated and cross-referenced to the original report, ensuring compliance with CPR 35.6(2)(a).
-
05
Draft & peer review
The addendum expert report is drafted, then reviewed by a second expert within our chambers to ensure consistency, clarity, and adherence to CPR Part 35 before finalisation.
Every stage of litigation
may require an addendum.
Our chambers accepts instructions for supplementary expert reports across all procedural stages, from pre-action to trial. Each addendum expert report is tailored to the specific requirements of the court or tribunal.
Questions from
solicitors we work with.
When is an addendum expert report required under CPR Part 35?
An addendum expert report is required when new evidence emerges, the claimant’s condition changes, or Part 35 questions are raised by the opposing party. Our chambers ensures each update complies with CPR 35.3 and Practice Direction 35, maintaining the expert’s duty to the court.
Can a supplementary expert report address credibility issues?
No. Credibility is a matter for the court. Our experts may address symptom validity or consistency of presentation but cannot opine on the claimant’s truthfulness, as this would breach CPR 35.3 and the Civil Justice Council’s 2014 Guidance.
How quickly can our chambers prepare an addendum expert report?
10–14 days. Our chambers prioritises addendum expert reports to meet court deadlines, with expedited turnaround available for urgent instructions. The timetable is confirmed at intake, ensuring compliance with CPR 35.6(2)(b).
Is a supplementary expert report admissible if served late?
Only with court permission. Late service risks exclusion under CPR 35.13. Our chambers coordinates with instructing solicitors to ensure timely filing and service, avoiding procedural challenges under CPR 35.14.
Can an addendum expert report be used in joint expert discussions?
Yes. Our experts use the addendum expert report as the basis for joint discussions under CPR 35.12, ensuring all parties engage with the updated evidence and reasoning before the joint statement is finalised.
Does an addendum expert report require a new declaration of truth?
Yes. Every supplementary expert report includes a fresh CPR Part 35 declaration and statement of truth, confirming the expert’s continuing duty to the court and the accuracy of the updated evidence.
Need an addendum expert report
for your case?
Send the original report, new evidence, and the reason for the addendum. Our chambers will confirm scope, expert availability, and a CPR-compliant timetable within one working day.