Supreme Court gives guidance on the admissibility and use of expert evidence


Rachel Barrett discusses Kennedy v Cordia (Services) LLP, in which the Supreme Court has given detailed and practical guidance on the admissibility and use of expert evidence in the course of a judgment concerning the remit of employers’ duties to take care for their employees’ safety at work.

Background to the appeal

Miss Kennedy worked for Cordia as a home carer. On the evening of 18 December 2010 she slipped and fell on an icy footpath leading to the home of one of her clients, injuring her wrist. Cordia had carried out risk assessments which identified the danger of falls when travelling between work locations but had not considered the possibility of issuing its employees with anti-slip attachments designed to increase traction in icy conditions.

Miss Kennedy brought a claim for personal injury that was heard in the Outer House of the Scottish Court of Session. She relied on evidence from Mr Greasly, an engineering consultant with significant experience in advising companies on health and safety risks.  He would have assessed the risk of injury in such circumstances to be “substantial” rather than “tolerable” (as was Cordia’s assessment). He explained that a number of employers provided such anti-slip attachments which reduced the risk of falls on snow or ice.

Cordia objected to the admission of Mr Greasly’s evidence on the basis that he did not have any relevant special skill to qualify him to act as a skilled witness. However, the Lord Ordinary rejected this submission. He found that Cordia’s risk assessments had been inadequate, in breach of the Management of Health and Safety at Work Regulations 1999 (the Management Regulations), and there had been a failure to take relatively simple precautions to reduce risk, in breach of the Personal Protective Equipment at Work Regulations 1992 (the PPE Regulations). He also found Cordia liable in negligence under the common law.

The Lord Ordinary’s decision was reversed by an Extra Division of the Inner House of the Court of Session. They held that Mr Greasly’s evidence should not have been admitted, doubting that health and safety was an area calling for expertise with a recognised body of science and experience. They did not consider that the accident occurred while Miss Kennedy was “at work” for the purposes of the PPE Regulations. Further, in their view it had not been proven that wearing the attachments would have made any material difference to Miss Kennedy’s accident.

The Supreme Court’s decision

The Supreme Court unanimously allowed Miss Kennedy’s appeal. Lord Reed and Lord Hodge, the two Scottish Justices, gave a joint judgment with which Lady Hale, Lord Wilson and Lord Toulson agreed.

Expert evidence

Lord Reed and Lord Hodge recognised the need to regulate skilled witness evidence which can be excessively influential (although this is more a risk with a lay jury than a judge) and difficult for the other party to test unless assisted by expert advice themselves. They therefore set out detailed guidance regarding the admissibility of skilled or expert evidence, the responsibilities of the party’s legal team and the court in relation to such evidence, and the importance of economy in litigation.

Admissibility: Skilled witnesses may give both opinion evidence and expert evidence of fact, drawing on their own knowledge and experience of the subject matter including the work and literature of others. The four considerations governing the admissibility of skilled evidence are set out at para.44 of the judgment:

“(i) whether the proposed skilled evidence will assist the court in its task;

(ii) whether the witness has the necessary knowledge and experience;

(iii) whether the witness is impartial in his or her presentation and assessment of the evidence; and

(iv) whether there is a reliable body of knowledge or experience to underpin the expert’s evidence.”

Further helpful guidance is given in the judgment in respect of each of the four considerations. These considerations apply equally to the admissibility of both to expert evidence of fact and opinion, save that when the first consideration is applied to opinion evidence, the threshold test is higher, namely whether the proposed evidence is necessary. (There are no special rules on the admissibility of factual evidence in the case; for example, Mr Greasly gave evidence about the sloping path where Miss Kennedy fell.)

Lawyers’ responsibilities: The legal team of a party proposing to adduce expert evidence must assess the witness’s expertise and whether his or her evidence is otherwise properly admissible. They must also ensure that he or she is aware of the duties imposed on an expert witness and disclose all of the relevant factual material to the witness.

Responsibilities of the court: When assessing whether and to what extent to give weight to expert evidence, the judge should “test the evidence to ascertain that it complies with the four considerations … set out … above and is otherwise sound” (para.59).

Economy in litigation: The judgment notes concerns regarding the costs of civil litigation and encourages courts’ use of case management powers to reduce expense, for example by directing statements of agreed facts, joint expert reports, and jointly instructed experts.

On the issue of expert evidence, the Supreme Court concluded that Mr Greasly’s evidence had been properly given and considered. In the course of the appeal, counsel for Cordia had (correctly, in the view of the court) conceded that health and safety practice could be the subject of expert evidence. Lord Reed and Lord Hodge held that all of the factual evidence given by Mr Greasly had been rightly admitted, and while he had made statements of opinion on Cordia’s legal duty, “an experienced judge… could readily treat the statements as the opinions of a skilled witness as to health and safety practice… and make up his own mind on the legal question.”

The law on health and safety at work

The judgment traces the EU law origins of our statutory framework governing health and safety at work, and gives a useful summary of the underpinning principles. These include the importance of risk assessment, followed by risk avoidance, then risk reduction, and that collective protective measures, where feasible, are preferable to individual measures, which in turn are preferable to merely issuing instructions to employees.

Lord Reed and Lord Hodge have endorsed the approach advocated by Smith LJ in Allison v London Underground Ltd [2008] EWCA Civ 71; [2008] ICR 719; in that “the most logical way to approach a question as to the adequacy of the precautions taken by an employer was through a consideration of the suitability and sufficiency of the risk assessment” (para.89). Therefore, whether there has been a “suitable and sufficient” risk assessment for the purposes of reg.3 of the Management Regulations is an anterior question to whether “suitable personal protective equipment” has been provided in compliance with reg.4 of the PPE Regulations. The Lord Ordinary’s conclusions in respect of these questions were ones he was entitled to reach on the evidence before him, and it was reasonable to infer that the failure to provide the PPE caused or materially contributed to the accident. Further, an employee is “at work” for the purposes of both the Management Regulations and the PPE Regulations throughout the time when she is in the course of her employment, and therefore Miss Kennedy had the benefit of these statutory protections as she traversed the icy path to her client’s door.

In relation to common law liability, the Justices pointed out that Miss Kennedy was not in the same position as an ordinary member of the public using the footpath; she had an important obligation to reach her elderly and ill client to provide care in the course of her employment and therefore had no choice but to use the path. An employer’s duty goes beyond taking common precautions and may encompass an obligation to seek out risks which are not in themselves obvious. In this regard, the court preferred the modern formulation of the duty of care in Baker v Quantum Clothing Group Ltd [2011] UKSC 17; [2011] 1 WLR 1003, para 9 to the older test in Morton v William Dixon Ltd 1909 SC 807, 809 cited by the Extra Division. (This had required the pursuer to show that the precaution contended for was either commonly taken or obviously needed.) Further, the duty on employers to carry out a risk assessment is not merely statutory but is “logically anterior to determining what precautions a reasonable employer would have taken in order to fulfil his common law duty of care” (para.110).


The guidance on skilled witnesses is given in relation to Scots civil law, but is readily cross-applicable to the English law on expert evidence. While the judgment considers the use of expert evidence regarding health and safety practice, it is also more widely applicable to other areas of expertise. Where there is any doubt as to the admissibility of proposed expert evidence, this judgment can be used as a checklist by lawyers in advising their clients on litigation strategy.

It should be noted that at the time of Miss Kennedy’s accident, the Management Regulations and the PPE Regulations gave rise to civil liability for a breach that caused injury. Since s.69 of the Enterprise and Regulatory Reform Act 2013 came into force on 1 October 2013, breach of most health and safety regulations is merely a basis for establishing liability under the common law of negligence. The judgment confirms and emphasises that the obligation to risk assess forms part of the employer’s common law duty of care.  

Lastly, employers whose employees work outdoors in snow and ice may also wish to investigate anti-slip attachments if they do not provide these already.  Following the Kennedy v Concordia (Services) LLP decision, it will be difficult for employers to argue that they were reasonably unaware of this precautionary measure.