Overstepping the boundaries: expert evidence and duties of independence

Patricia Andrews & Others v Kronospan Ltd (Andrews) [07.03.22]

The case of Patricia Andrews & Others v Kronospan Ltd (Andrews) [07.03.22] is a stark reminder of what can go wrong when expert witnesses do not fully understand their duties, and lawyers overstep the limits of their role when instructing them.


This case concerned a group litigation raised by 159 residents of Chirk, Wrexham, all of whom lived next to the defendant’s wood processing and manufacturing plant. The claimants alleged that the defendant was liable to them in nuisance as a result of dust noise and odour emissions coming from the defendant’s plant.

Both parties were granted permission to rely on the evidence of an expert in dust modelling and analysis and the court directed the experts to prepare joint statements of their evidence.

Application to revoke permission to rely on expert evidence

In December 2021, the defendant’s solicitors became aware of regular discussions (by phone and email) between the claimants’ solicitors and their expert in the period from May to November 2021. It was discovered that working drafts of the joint statement were being shared between the expert and the solicitors and that the solicitors had provided commentary on the drafts. 

In response, the defendant made an application to revoke the claimants’ permission to rely on the evidence of the expert. The defendant argued that the actions of the claimants’ expert and solicitors amounted to a breach of the Civil Procedure Rules (which state that solicitors should not be involved in joint statement discussions) and that the only appropriate sanction was to revoke the claimants’ permission to rely on their expert’s evidence.

The claimants’ solicitors accepted that their conduct had been inappropriate and that at least 16 of the comments made by them in communications with the expert related to “advice and suggestions as to content”. However, they argued that the expert only changed his position once as a result of their feedback, and that to revoke permission at this stage would be “potentially disastrous” for the claimants, who had already paid their expert £255,000 in fees over the course of three years.

Court’s decision

The High Court concluded that the “serious transgressions by the claimants’ solicitors and [the expert] are such that the court has no confidence in [his] ability to act in accordance with his obligations as an expert witness”. It was therefore appropriate to revoke the permission granted to the claimants to rely on the expert’s evidence. 

In considering the application, the judge noted that the communications were “continuous” and that the expert’s comments in some of the correspondence were strongly indicative of the expert trying to support the claimants’ case. The judge held that: “it is important that the integrity of the expert discussion process is preserved so that the court, and the public, can have confidence that the court’s decisions are made on the basis of objective expert evidence”.


Unlike in England, there are no statutory rules governing the duties of an expert witness in Scottish litigation. However, the same broad principles apply.

For example, the Supreme Court in Kennedy v Cordia [2016] held that the guidance on expert duties set out in the case of National Justice Compania Naviera SA v Prudential Assurance Co Ltd (The Ikarian Reefer)(No 1) [1993] should be applied in Scottish civil cases. 

The ‘Ikarian Reefer principles’ include:

  • Expert evidence presented to the court should be, and should be seen to be, the independent product of the expert, uninfluenced as to form and content by the exigencies of litigation”.
  • “An expert witness should provide independent assistance to the court by way of objective, unbiased opinion in relation to matters within his expertise. The witness should never assume the role of an advocate”.

These principles have several important applications:

  1. The decision in Andrews is a timely reminder of just how important it is for instructing solicitors to clearly set out an expert’s duties and their practical implications in writing at the point of instruction.
  2. Caution should be taken when liaising with an expert in relation to their substantive evidence, bearing in mind that any attempt to directly influence an expert’s opinion is likely to be improper.
  3. There are no rules in Scotland concerning joint statements of experts, but when a joint statement is ordered, the same principles of transparency and candour apply. In the Andrews case, much was made of the expert’s failure to include the defendant’s expert in correspondence. It follows that where there is an order for cooperation between experts, communications should remain strictly between experts and if separate input is required from solicitors or the court, an expert should consider giving their opposite number advance notice that they intend to raise a specific matter with their instructing agents before doing so.

Andrews illustrates that these principles are not just best practice - they are fundamental to the roles of the expert and instructing solicitor. The lesson of Andrews is clear: depart from them at your peril.

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