PSYC 3320 Lecture 7

Introduction to Expert Testimony

• Discussion of expert testimony and expert witnesses in the court system.

• Importance of considering philosophical questions about their role and necessity.

  • Should expert testimony be allowed?

  • What is the criteria for determining an expert?

  • When is an expert necessary?

  • Should expert testimony be required in all cases?

Role of Expert Witnesses

• Expert witnesses differ from regular witnesses:

  • Regular witnesses (like eyewitnesses) can only provide accounts of facts they have directly observed.

  • Expert witnesses provide interpretations and educated opinions about events they did not witness.

• Purpose:

  • To inform the jury and judge, who may not have specialized knowledge on the subject matter being discussed.

Admissibility of Expert Testimony

• Expert testimony is considered evidence and must meet specific admissibility standards.

• Variability in courts regarding how expert testimony is treated:

  • Some courts restrict expert testimony due to perceived prejudice against jurors.

  • Others allow more leeway, trusting that jurors can weigh expert opinions appropriately.

• The importance of cross-examination in adversarial systems:

  • Aims to provide jurors with comprehensive information about expert testimony's credibility.

Qualifications of an Expert

• An expert is defined as someone qualified by knowledge, skill, experience, training, or education.

• Vagueness in defining expert qualifications leads to subjective interpretations in court.

• Typical experts in eyewitness psychology:

  • Often college or university professors with research and teaching backgrounds in cognitive or social psychology.

Standards for Admitting Expert Testimony

Fry Standard

• Established in Fry v. United States involving a polygraph test.

• Key takeaway: Testimony must be based on scientifically sound principles accepted in the relevant field.

  • Emphasizes that courts recognize that not all research finds uncontested acceptance.

• Pros: Focuses on scientific validity.

• Cons: Ambiguities in "general acceptance" of scientific evidence.

Federal Rules of Evidence (FRE)

• Introduced to provide uniform evidentiary rules.

• Key rules affecting expert testimony:

  • Rule 403: Relevant evidence may be excluded if its probative value is outweighed by the risk of unfair prejudice or misleading jurors.

  • Rule 702: Expert testimony is admissible if the expert has specialized knowledge helpful to the trier of fact.

• Attention to the expert’s qualifications rather than general scientific acceptance.

Daubert Standard

• Judges assess the admissibility of expert testimony based on reliability and relevance rather than general acceptance.

• Criteria to consider:

  1. Falsifiability of the expert's theory or techniques.

  2. Error rate associated with the technique.

  3. If the theory or technique has been peer-reviewed.

  4. General acceptance in the scientific community.

• Concerns arise around the judges' ability to evaluate scientific validity due to lack of scientific expertise.

Variability in Expert Testimony Handling

• Differences across states and types of evidence:

  • Eyewitness testimony can be treated differently from forensic evidence (e.g., blood splatter).

• Research indicates variability in judges’ acceptance of expert testimony and how they conduct reviews on expert credibility.

The Canadian Context

• Canadian courts follow a general relevancy approach rather than strict standards.

• The Supreme Court of Canada has not established a clear standard for lower courts on expert testimony admissibility.

• Criteria from Canadian cases include relevance, necessity, and the qualifications of the expert.

The Need for Expert Testimony

• Questions surrounding the necessity of expert testimony arise, particularly in the domain of eyewitness reliability.

• Empirical research shows gaps in judges’ and jurors’ understanding of factors affecting eyewitness memory.

• Importance of expert testimony in educating judges and jurors about memory fallibility in legal proceedings.

Safeguards for Eyewitness Testimony

• Judicial Instructions: Judges provide directions to juries regarding the reliability of eyewitness testimony, though their effectiveness is debatable.

• Cross-examination: Traditionally a safeguard, but may not effectively challenge eyewitness statements as intended.

• Exclusion of Evidence: Courts can decide to exclude both eyewitness and expert testimonies if deemed inappropriate or uncorroborated.

Summary

• Eyewitness testimony is prevalent despite its potential unreliability, making expert consultation critical.

• Experts do not determine if eyewitness accounts are wrong but help in understanding the factors that affect their accuracy.

• Focus on enhancing jurors' awareness of memory issues to aid in fair legal proceedings.