Expert Witnesses and Admissibility of Evidence

Role of Psychologists in the Courtroom

Expert Witness

  • An expert witness is someone with specialized knowledge, skills, education, or experience in a particular field. They are called upon in legal proceedings to provide expertise and assist the court in understanding complex technical or scientific issues.
  • Medical doctors were among the first to advise judges, appearing at the Old Bailey approximately 600 years ago.
  • Around 1620, a jury was provided with expert testimony for the first time.
  • Since the 1980s, the demand for psychologists as expert witnesses has increased significantly.
  • Areas with increasing involvement of psychologists as experts:
    • Syndrome evidence
    • Confessions by suspects
    • Eyewitness testimony
    • Family law
  • Whether a witness qualifies as an expert is a factual question for the judge to decide.
  • Specific knowledge acquired through scientific study or experience can qualify a witness as an expert (Cattermole, 1984:126).

Admissibility of Expert Witness

  • The treatment of expert testimony by psychologists in courts has seen significant developments across various areas.
  • In Daubert v. Merrell Dow Pharmaceuticals, the US Supreme Court established criteria for deciding whether expert evidence is admissible.
  • English courts have opened the door to psychologists as expert witnesses without abandoning the 'common knowledge and experience rule' (R v. Turner [1975]).
  • Courts in Australia, New Zealand, and Canada have adopted a more liberal approach to interpreting the common knowledge rule in recent cases.

Role of Expert Witness

  • Common law distinguishes between facts and inferences drawn from those facts.
  • Witnesses typically state facts they have directly observed and do not give opinions.
  • An exception is made for expert witnesses when:
    • The issue requires expertise beyond the knowledge and experience of the magistrate, judge, or jury.
    • The witness qualifies as an expert.
  • In some jurisdictions (e.g., the United States), an expert witness can express an opinion on the ultimate issue that the tribunal must decide.

Four Roles for Forensic Psychologists (Haward, 1981a)

  1. Experimental:
    • Informing the court about the state of knowledge relevant to a cognitive process.
    • Conducting experiments directly relevant to the case (e.g., eyewitness testimony, phobia claims).
  2. Clinical:
    • Testifying on assessments of a client's personality, IQ, neuropsychological functioning, mental state, or behavior.
  3. Actuarial:
    • Estimating the probability of an individual living independently or being gainfully employed in civil cases involving psychological deficits caused by negligence.
  4. Advisory:
    • Advising counsel before or during a trial about questions to ask witnesses, including opposing expert witnesses.
    • The presence of another psychologist evaluating testimony can increase an expert's stress levels.

Krauss and Sales (2001)

  • Krauss and Sales (2001) investigated whether mock jurors are more influenced by clinical opinion or actuarial expert testimony in a Texas death penalty case involving dangerousness.
  • Mock jurors weighed clinical expert opinion more heavily than actuarial expert testimony.
  • The authors noted that actual jurors may react differently to the experimental conditions.

Five Rules for Admitting Expert Evidence (Freckelton and Selby)

  1. Expertise rule: Does the witness have sufficient knowledge and experience to qualify as an expert?
  2. Area of expertise rule: Is the claimed knowledge credible to others capable of evaluating its foundations?
  3. Basis rule: To what extent can an expert's opinion be based on matters outside their direct observations? Reliance on unevaluable material is problematic.
  4. Common knowledge rule: Is the information sought from the expert something the tribunal needs help with, or can they rely on general knowledge?
  5. Ultimate issue rule: Will the expert's contribution supplant the tribunal's function in deciding the issue?

'Hired Gun' Effect

  • Cooper and Neuhaus (2000) conducted a mock-juror study involving a legal case about the cause of the plaintiff's cancer.
  • Findings:
    • Experts who are highly paid and testify frequently are perceived as 'hired guns.'
    • They are less liked and believed, especially if their testimony is complex.

Expert Witnesses in Different Countries

  • Legal proceedings and the roles of expert witnesses vary across countries.
  • In Western common law countries, expert witnesses testify for the side that retains and pays them.
  • In continental European jurisdictions, expert witnesses are appointed by the court.
  • Court-appointed experts generally have higher status than privately-retained ones.
  • Freckelton and Selby (2005) note that courts are increasingly appointing 'referees' to report on specific issues.
  • Retired judges are sometimes used to expedite dispute resolution.
  • 'Assessors' with expertise in specific areas may sit with a judge to answer questions related to their expertise.

Duties of an Expert Witness in a Criminal Trial (R v. Harris [2005], R v. Bowman [2006])

  • Whether instructed by prosecution or defense, expert witnesses have specific duties:
    1. Evidence should be independent and free from the influence of litigation.
    2. Assist the court by providing objective, unbiased opinion within their expertise.
    3. State the facts and assumptions underlying their opinion, including those that might detract from it.
    4. Acknowledge when an issue falls outside their expertise.
    5. If their opinion is based on insufficient data, state that it is provisional.
    6. Communicate any change of opinion on material matters to the other side and the court.
  • The court emphasized that experts should be objective and impartial.

Expert Witness' Report

  • The report should contain:
    • Details of the methodology used for research.
    • Indication of whether the research was under the expert’s supervision.
    • Relevant extracts of literature or other material.
    • A statement that the report was compiled in accordance with the stated duties.

United States: Expert Testimony

  • The practice of providing expert testimony for a fee became widespread in the United States in the mid-19th century.
  • Between 1850 and 1920, the test for admitting expert testimony was whether the expert was qualified to render an opinion on the issue.

Frye v. United States (1923)

  • The District of Columbia Court of Appeals rejected testimony from a lie-detector expert because:
    • The scientific theory was not generally accepted in the relevant professional community.
    • A request to conduct the test in the jury's presence was denied.
  • The Frye decision established 'general acceptance in the particular [scientific] field' as the standard for admitting expert testimony.

FRE & Frye

  • The Frye test became frequently cited in court decisions in the United States in the early 1980s.
  • Frye was a vague ruling that led to American courts admitting expert testimony in a broad range of fields without much scrutiny.
  • Critics pointed to Frye's lack of clarity and undue rigidity, arguing that it contradicted the Federal Rules of Evidence (FRE) 1975, which aimed to admit all reliable evidence unless misleading.
  • The FRE included a modified standard: scientific evidence must be relevant and reliable.
  • Both FRE and Frye standards were applied until the US Supreme Court's decision in Daubert v. Merrell Dow Pharmaceuticals in 1993.

Daubert v. Merrell Dow Pharmaceuticals

  • The case concerned the exclusion of expert evidence that a drug, Bendectin, caused birth defects.
  • The Supreme Court ruled that:
    • The Frye 'general acceptability' standard was too austere and not part of federal evidence law.
    • The Frye standard should be replaced by the FRE standard.
  • The ruling in Daubert emphasized 'vigorous cross-examination, presentation of contrary evidence, and careful instruction' as the test for expert witnesses.

Daubert Judgement Details

  • The Daubert judgement stated that:
    • Expert testimony must be 'scientific knowledge' derived by the scientific method.
    • The scientific status of a theory relies on its falsifiability or testability.
    • Peer review and publication are also pertinent considerations.

Three Judicial Criteria for Expert Witness Admissibility

  1. Relevancy: Scientific evidence must relate to the specific case.
  2. Legal sufficiency: Expert evidence must not confuse, mislead, or prejudice the jury but provide evidence or proof (probative value).
  3. Reliability is decided based on four standards:
    • Has the technique or theory been tested?
    • What is the error rate involved?
    • Has the technique or theory been peer-reviewed and published?
    • What is the general acceptance of the technique or theory in the scientific community?

Implications of Daubert Ruling

  • The US Supreme Court expressed confidence in judges' ability to assess the scientific status of theories or techniques without scientific training.
  • Achieving this requires lawyers to possess 'cross-disciplinary knowledge and understanding.'
  • The need for legal psychology courses for lawyers presents an opportunity for psychologists to communicate their expertise and bridge the gap between the disciplines.

General Electric Co. v. Joiner (1997)

  • The Supreme Court addressed whether exposure to chemicals contributed to Joiner's lung cancer.
  • The trial judge excluded expert testimony because it did not rise above 'subjective belief or unsupported speculation,' lacking a scientific link.
  • The Supreme Court reinstated the trial judge’s exclusion, stating that the legal standard for expert testimony is the same as the relevant professional community's standard.

Kumho Tire Co. v. Patrick Carmichael (1999)

  • The US Supreme Court addressed whether Daubert guidelines apply to all forms of specialized knowledge.
  • The case involved expert testimony about a defective car tire causing an accident.
  • The court's decision:
    • Daubert factors may apply to testimony of engineers and other non-scientists.
    • The 'gatekeeping' obligation of the trial judge under Federal Rule of Evidence 702 (FRE 702) applies to all expert testimony.
    • FRE 702 does not distinguish between 'scientific', 'technical' or 'other specialized knowledge'.
    • The distinction between scientific and non-scientific evidence is unclear.
    • The judge has broad discretion in their gatekeeping role.
  • Kumho clarified that the Daubert analysis applies to scientific, technical, and other specialized knowledge.

Daubert, Kumho, and Joiner

  • Freckelton and Selby (2002) suggest the Supreme Court will likely apply the Daubert analysis to medicine and psychology.
  • Justice Breyer called on psychologists to help the judiciary identify valid psychological testimony.
  • The trilogy assumes that American judges can judge the scientific reliability and validity of scientific evidence.
  • Gatowski et al.'s (2001) findings suggest that judges struggle to assess the science which defeats the purpose of experts working with them.

England and Wales: Expert Testimony

  • Experts began testifying in English courts in the second half of the nineteenth century.
  • The English approach to novel scientific or psychological evidence has been more lenient than strict.
  • British courts have been unenthusiastic about expert evidence by psychologists until recently.
  • The landmark decision in R v. Turner (1975) established the 'common knowledge and experience' rule, making it difficult for psychologists to have their evidence accepted.

Common Knowledge and Experience' Rule of Evidence

  • Lord Mansfield ruled in Folkes v. Chadd (1782) that expert opinion is admissible if it provides information outside the jury's common knowledge.
  • Lawton LJ stated in Turner that expert opinion is unnecessary if the judge or jury can form their own conclusions without help.
  • Impressive qualifications alone do not make an expert's opinion on human nature more helpful than the jurors' own judgment.

Critique of Turner

  • The Turner decision suggests that courts in England and Wales do not need a psychologist's expert knowledge except in cases of mental abnormality.
  • Colman and Mackay argue that the 'human behaviour is transparent' assumption is false.
  • They cite psychological knowledge in areas like the 'fundamental attribution error' (Miller et al., 1990), obedience to authority (Milgram, 1974), group polarisation (Isenberg, 1986), cognitive dissonance (Wickland and Brehm, 1976), and bystander intervention (Latane and Naida, 1981).
  • Colman and Mackay conclude that expert psychological evidence should be admitted when it is relevant and potentially helpful in explaining behaviour not easily understood with common sense.

The Impact of Expert Testimony by Psychologists

  • The impact of expert testimony can vary, from damages awarded in civil suits to jurors' assessment of reliability, verdicts in criminal cases, and freeing wrongly convicted individuals.
  • Researchers have reported that juror decision-making is influenced by expert testimony on:
    • The fallibility of eyewitness identifications
    • Clinical syndromes (e.g., battered wife syndrome, rape trauma syndrome, child sexual abuse syndrome, and depressed memory syndrome)
    • Insanity
    • Future dangerousness of a defendant.

India: Expert Witness and Admissibility

  • What is the law regarding expert witnesses?
  • What is the rule of admissibility?
  • What is included in this rule?