Witness Evidence Guidelines and Expert Opinions

General Rule on Witness Evidence
  • Witness Testimony: A witness may only give evidence based on facts they personally perceived.
  • Exceptions:
    • Non-Expert Opinions: Allowed in relation to commonplace occurrences, where the witness's perception is deemed relevant.
    • Expert Opinions: Allowed by witnesses qualified to give expert opinions regarding specialized knowledge.
Non-Expert Opinion
  • Definition: Statements of opinion a non-expert may provide, which can convey perceived facts without requiring specialized knowledge.
  • Examples of Non-Expert Opinions:
    1. Identification: Identifying an object, handwriting, or voice that the witness is familiar with.
    2. Physical Attributes: Commenting on someone's age, general appearance, health, mental state, or emotion.
    3. Speed: Observing and describing the speed of a vehicle.
Expert Opinion
  • When to Call Expert Opinions:
    • Relevant to subject matters requiring expertise that a layperson cannot adequately understand without assistance.
    • Inadmissibility: If the fact-finding tribunal can form opinions independently, expert testimony may be unnecessary.
Responsibilities of Parties in Litigation
  • Altering the Court: Parties must alert the court early if they wish to introduce expert evidence.
    • Importance of Pre-Trial Preparation Hearing (PTPH): Discussing matters relating to expert evidence.
Competence of Expert Witnesses
  • Determining Competence:
    • Statutory qualifications may specify what is required to provide expert opinions in certain cases.
    • Competence can derive from:
    • Formal education
    • Training
    • Professional experience
Opinions on Ultimate Issues
  • Allowed: Experts can provide opinions on ultimate issues, provided that the jury retains the ability to form their own conclusions.
  • Clarification to the Jury: When submitted, it must be clear that the jury is not bound by the expert opinion and must decide the issue independently.
Duty to the Courts
  • Experts' Obligation: Experts are required to assist courts in fulfilling their overriding objectives by providing unbiased opinions within their areas of expertise.
  • Overrides Duty to Client: An expert's duty to the court is paramount, even if it conflicts with their obligations to the party employing them.
Key Summation

  1. General Principle:

    • Ordinary inadmissibility of opinion evidence; witnesses limit their testimony to personally perceived facts.
    • Exceptions include both non-expert and expert opinions.

  2. Expert Assistance Requirement:

    • Experts must aid the court's goals, and their obligations to the court take precedence over those to any retaining party.
Examples of Expert Requirement Considerations
  • Fingerprint Analysis: Requires expert testimony since this knowledge is outside that of a lay person.
  • Jewelry Valuation: Expert testimony in this area is irrelevant to commission of an offense, rather applied in sentencing.
  • Diminished Responsibility: Expert evidence on this aspect is only admissible in murder cases.
Conclusion
  • Experts must properly define their expertise in reports and during testimonies by:
    • Outlining limitations of knowledge.
    • Informing parties of any changes to their opinions since prior reports or statements.
  • Essential Qualities: Opinions must remain objective and unbiased, keeping court duties above any financial or contractual obligations.