16. Expert Witness Testimony Flashcards
What is required for expert opinion/conclusion?
(PQRS)
1) Probability (reasonable) re opinion
- NOT mere guess/speculation
2) Qualified as expert
- Scientific/Specialised/Technical knowledge
- Experience
- Training/Education
3) Relevant & Reliable
- Subject matter where specialised knowledge would help trier of fact understand issue
- Sufficient fact/data
- Reliable principles and methods
- Reliable application of principles and methods
4) Supported by proper factual basis
- NOT legal basis
- Expert’s personal observation
- Facts made known to expert at trial (often by hyopthetical questions)
- Facts made known to expert outside trial (not personally known + reasonably reliable by related experts)
- NO need to testify re facts
How can a scientific technique be considered reliable?
(TRAP) - Daubert factors
1) Tested theory/technique
2) Rate of error (potential/known)
3) Accepted in scientific community
4) Peer review + publication
For what purpose may expert opinion/conclusion be used/not used?
To prove ultimate issue in case
NOT to prove mental state for crime/defence (criminal case)
When may an expert be cross-examined on his statement contained in any scientific publication (treatises/texts)?
1) Reliable according to;
- Expert’s testimony (direct/cross-exam)
- Another expert’s testimony
- Judicial notice
2) Relied on;
- By expert (direct exam)
- By witnesses (cross-exam)
How may an expert’s statement in publications be used?
Expert opinion
Impeachment (of expert) (cross-exam)
Substantive evidence (non-hearsay) (direct exam)
1) Expert must be on stand while statement is read into evidence
2) Read into evidence = Show to jury
- NOT read as exhibit
What is the difference between expert witness and lay witness?
Expert witness
- Specialised knowledge
Lay witness
- NO specialised knowledge
Who determines whether expert witness opinion is admissible?
Judge
- Even if Expert lacks training
