‘Cross-Examination of Expert Witnesses’

As I write a ‘Case Preparation & Advocacy’ Practice Note for the 2nd edition of the Contentious Probate Handbook, which I am working on over the next 6 weeks, I will put up a series of short extracts from the Practice Note as posts. Today’s post is about one of the most formidable challenges for any advocate in a Contentious Probate Trial – cross-examination of an eminent experts. Note also that in this context, Dr Hugh Series who is a NHS Consultant in old age psychiatry and a member of the Faculty of Law at the University of Oxford, is contributing a separate standalone Practice Note for inclusion in the book as an Appendix about ‘Mental disorders.’ The extract from the Practice Note I am currently drafting is: –


  1. The weight to be attached to expert evidence is entirely a matter for the trial judge.
    1. An advocate who can state the opposing expert’s case theory, opinions, assumptions, inferences, chain of reasoning, and conclusions better than the opponent’s expert witness can, is standing on the mountain top and looking down, for the purposes of:

1.2.1 distinguishing his own expert’s case theory, opinions, assumptions, inferences, chain of reasoning, and conclusions; and

  1. conducting a devastating ‘top down’ forensic critique of the opposing expert’s evidence, in order to: cast doubt; demonstrate falsity; tarnish; ridicule; and comprehensively devalue the weight to be attached to that evidence.

1.3    ‘Research, as much as technique, lies at the heart of expert witness cross-examination. Counsel cannot conduct an adequate cross examination without first thoroughly investigating all of the technical aspects of the expected testimony. It is often said that you cannot cross-examine an expert without first becoming an expert yourself. Moreover, your research should extend beyond the expert’s subject matter area and into the witness’s own professional background … There is nothing so effective as impeaching an expert with his own prior assertions.’ (Lubet).