When is expert evidence not expert evidence?

  • Published: June 26, 2018
  • Author: Paul Sankey, Partner, Enable Law

In a recent family case, a judge rejected the evidence of an expert on the grounds that it was not expert evidence at all[1]. The case is a reminder of the basic principles governing the admission of expert evidence.

The case concerned a mother's application to discharge a care order for her eight-year-old son, L. The right to make that application is set out in section 39 of the Children Act 1989. The Local Authority contested the application, arguing that the child had, over a two-and-a-half-year period, formed an 'attachment' to his foster carers. It relied on evidence from a social worker as the child's 'attachment profile'.

The judge was concerned that, if forming an 'attachment' with a foster carer was enough to frustrate an application, a parent's right under section 39 would be largely meaningless. The application would only be made by someone who had not been caring for their child for an appreciable period and where the child will have formed an attachment to someone else.

The judge went back to first principles as to when expert evidence is admissible.

Expert evidence in civil proceedings is admissible if it is:

1. contained within a recognised body of expertise governed by recognised standards and rules of conduct relevant to the question which the Court has to decide; and

2. of such a nature that a person without instruction or experience in the area of knowledge or human experience would not be able to form a sound judgment on the matter without the assistance of witnesses possessing special knowledge or experience in the area.

The Court nevertheless controls whether parties can rely on it. In family proceedings, it must be 'necessary' to assist the Court to resolve proceedings.

The judge considered the social worker's explanation of attachment theory. The theory describes "the dynamic relationship that develops between an infant and their primary carer".

In his view, it did not satisfy either criterion.

With regard to the first, there was no evidence it was the subject of any specific recognised body of expertise governed by recognised standards and rules of conduct.

With regard to the second, it was only a theory and "might be regarded as a statement of the obvious, namely that primate infants develop attachments to familiar caregivers…"

The judge said:" For my part I would say with all due respect that I do not need a social worker to give me evidence based on this theory to help me form a judgment about L's attachments" and "I cannot say that this so-called expert evidence has assisted me in reaching the decision I must make".

He went on to say: "In my judgment, in any future case where it is proposed that expert evidence of this nature is adduced I would expect the Court to determine the application with the utmost rigour, and with the terms of this judgment at the forefront of its mind."

The story shows the importance of going back to first principles and understanding the basis on which expert evidence is admissible. It must meet the two-fold test of being (1) part of a recognised body of expertise with its own standards and rules and (2) being such that the Court cannot form a sound judgment without the assistance of witnesses with that expertise.

If you enjoyed reading this article, you might also be interested in Paul Sankey's blog, 'When an expert's evidence is fundamentally flawed'.


[1]GM v Carmarthen County Council and LLM [2018] EWFC 36


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