Joint Expert Pendulum Testing Instructions

When single joint experts are appropriate

The Civil Procedure Rules favour single joint experts where:

• The amount in dispute is modest relative to expert costs
• The technical issue is bounded and not subject to legitimate ranges of opinion
• Both parties' interests are served by an independent factual record
• The court directs joint instruction at case management

Pendulum slip testing typically meets these criteria — it produces a measurement, not an opinion, and the methodology is well established.

How joint instruction works in practice

• Both parties' solicitors agree on the expert (us) and the joint letter of instruction
• The letter specifies the issues to be addressed, the access arrangements, and the cost-sharing
• The expert attends the site once, with both parties' representatives notified and invited if they wish
• The report is delivered to both parties simultaneously
• If either party has questions, those questions are submitted in writing under CPR 35.6
• The expert's overriding duty is to the court

What the joint instruction letter should cover

• Description of the accident and surface in dispute
• Access arrangements (who provides access, when, with what notice)
• Test scope — what areas, what conditions, which standards
• Documentary disclosure to be provided to the expert
• Photographs and any retained samples to be supplied
• Witness statements (if any) the expert is to consider
• Cost basis (typically split equally between the parties)
• Deadline for the report

Independence within joint instruction

Joint expert work does not mean compromise reporting. The duty under CPR 35 is to the court. Where the test data favours one party clearly, the report says so — even where both parties hoped for ambiguity. The benefit to both parties is that the report is far less open to attack later, since both parties had equal opportunity to instruct on the methodology.

Pre-issue agreed expert

Some matters resolve without proceedings being issued, with the parties agreeing to instruct a joint expert at the pre-action protocol stage to break a deadlock on liability. We accept instructions on this basis and the report can be relied on subsequently if proceedings are eventually issued.