Expert Evidence in the Depp v Heard Trial

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It's hard to have missed the coverage of the Depp v Heard trial. Our analysis of the testimony of expert psychologist Dr Shannon Curry and expert psychiatrist Dr David Spiegel under cross-examination covers their strengths and foibles. Replay key moments and find out which tenets of expert evidence could have improved their performances in the box.

Dr. David Spiegel


Commentary on Dr Spiegel’s non-verbal cues has been ample and often identified as the reason for his lack of credibility in court. There are however several basic tenets of effective substantive expert witness evidence which Dr Spiegel’s testimony lacked and with which his evidence could have been significantly improved.

  • 0:30 – 1:30: the expert showed a lack of understanding or knowledge of court process; Dr Spiegel was not able to say whether a medical exam had been requested but rejected by Heard’s team.
  • 1:50 – 3:25: the expert demonstrated a lack of familiarity with the codes of his own profession. American Psychiatric Association guidelines make it unethical to offer professional opinion based on publicly available information without conducting an examination of the subject – the expert did not give a direct affirmation of this nor make it clear that he knew the rules and is familiar with what the cross-examiner recited.
  • 3:25 – 5:28: Dr Spiegel’s attempts to pre-empt the direction of the cross-examiner’s questions made him appear defensive and aggressive.
  • 5:30 – 10:50: Dr Spiegel failed to provide a clear answer to the cross-examiner’s question, answering at first that he had acted unethically according to the Goldwater principle, then that he had not. Dr Spiegel’s argument that the cross-examiner had misinterpreted the APA guidelines may have been valid and relevant even if long-winded, but his contradictory responses undermined his appearance of clear-mindedness and honesty.
  • 17:13 – 20:20 : Dr Spiegel failed to explain clearly technical distinctions (the difference between Intimate partner violence traits and the wider ‘cluster B’ traits). 
  • Dr Spiegel was not able to share sufficient materials and primary evidence on which to base his opinion that Mr Depp is an ‘idiot’. Did he call Mr Depp an idiot in passing in his report or did he rely on this term as a proper clinical descriptor of Mr Depp’s cognitive abilities? Clear and precise language is essential to any effective expert report.

Dr. Shannon Curry

Cross-examination on evidence of other experts

A significant part of each expert witness’s cross-examination involved having to account for their expert findings with reference to the evidentiary materials that were available to them, including the expert opinions of other witnesses.

This aspect of cross-examination often requires the expert to remain especially patient and transparent – questioning on the specifics of copious amounts of documentation and testimony can be time-consuming and especially overwhelming where the expert’s recollection fails them.

Dr Curry’s measured appearance in the box demonstrates several effective ways to diffuse the pressure in these circumstances:

  • 3:57 – 6:45: Dr Curry provided short direct responses to questions about expert witness Dr Connell Cowan’s evidence. The brevity and clarity of these answers supported Dr Curry’s credibility by demonstrating her composure and sincere attentiveness to the questioner. In contrast to Dr Speigel, Dr Curry’s qualifications of her responses and misleading questions were also short and direct before they tied back to her main answer (Cowan did not diagnose Heard with BPD but also does not use diagnoses as a part of his practice).
  • 7:45 – 11:20: the expert was specific about the extent of her recollection: in her recollection, Dr Banks testified that Heard had reported violence but did not comment on consent in the former couple’s interactions; she remembers that both Depp and Heard saw Dr Banks for assistance, but after a certain point it was primarily Heard who saw the doctor for prescription and therapy. Dr Curry’s willingness to provide clear and comprehensive responses supported her appearance of impartiality by demonstrating her undefensive and cooperative approach to cross-examination.
  • 13:48 – 14:52: where Dr Curry vehemently disagreed with the examining lawyer, the expert kept her answers direct and offered a concise alternative account of the facts as she understood them, i.e. that she did not dismiss the notes of another expert but that the notes she recalls are not the same ones adduced by the questioning lawyer.
  • 15:05 – 16:47: the expert admitted that she had neither the memory nor adequate materials on hand to answer the cross-examiner’s question. The response effectively conveyed her professional concern about answering questions requiring her to make broad or overly-generalised claims on the evidence.

Defending professionalism

Dr Curry’s stoicism and conviction in the face of questioning about her professional conduct provides some critical pointers to all experts on how to assert their transparency and professional integrity. 

  • 1:30 – 3:00: The expert could justify her actions in the context of her professional practice, in particular as a matter of necessity in the provision of her services:
    – She did not disclose her meeting with Mr Depp’s legal team prior to being engaged because of its irrelevance to the substance of her report
    – She met with Depp and his legal team because the person who retained attorneys was unable to attend her office and a meeting was necessary to determine the suitability of her qualifications for the purpose of the trial.
  • 3:10 – 4:05: The expert understood her obligations to the court and could reiterate her duty to the court when questioned about her innate bias in favour of Depp’s case: “my obligation is to the court as a fact finder”. She referenced her retainer as a source of this expert opinion about her obligations. The response not only strengthened a sense of the expert’s credibility but also allowed time for her instructing attorneys to defend her.
  • 5:42 – 7:00: The expert’s clarity about the timeline of events supported her answer in the negative to the cross-examiner’s questions. The expert affirmed her credibility through her display of sheer reasoning competence and the steadfast conviction in her detail-oriented recount.


  • Experts should always be familiar with their professional ethical obligations as well as their obligations to the court as an expert witness. Especially in cases where they will be cross-examined, experts should also aim to appear with an understanding of the court history (expert engaged and when, which motions have affected their own ability to access documents and other further evidence) of the matter.
  • Experts should answer questions as concisely as possible and avoid pre-empting the questioning path of the cross-examiner. Where the assumptions underpinning the questioning seems misinformed, the expert should qualify their answers with an explanation of the technical misinformation and how it affects their answer before finally confirming their answer in short.
  • Experts should remain patient with the cross-examiner and always offer their professional knowledge as a means of clarifying or assisting the understanding of the cross-examiner of the facts in issue.

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