Opinion / Experts Flashcards
What are the requirements for lay opinion testimony?
(a) Rationally based on witness’s perception
(b) Helpful to understanding the witness’s testimony or determining a fact in issue
(c) Not based on scientific, experty stuff
What are some factors for determining whether a lay witness’s testimony is “helpful”?
Extent to which it goes to the heart of the issue
Amount of factual matter covered by the opinion
Ability or inability to convey the information with plain old factual testimony
Extent to which the jury is well-positioned to draw its own inference from the facts
The need for the testimony
Extent to which only the observer could have understood what happened
What are the requirements for expert opinion testimony?
Generally, the expert’s testimony must be “reliable” under Daubert. Specifically, the rule requires:
(1) The expert is qualified
(2) The testimony is helpful
(3) The testimony is based on facts or data
(4) The testimony is the product of reliable principles and methods
(5) The expert reliably applied the principles and methods to the facts of this case
What are some of the “reliability” factors listed in Daubert and Kuhmo?
Daubert:
Theory or technique has been or can be tested
Peer review, publication
Known potential rate of error, whether standards exist for controlling error
General acceptance of the theory or technique
Kubmo (for technical expert):
Information or techniques are reasonably relied upon by others in the profession
What may an expert base his/her opinion on?
What if the bases are inadmissible themselves (e.g., hearsay)?
Facts or data in the case that the expert has been made aware of or personally observed. Hearsay is not excluded.
When must an expert disclose underlying facts or data?
On cross-examination, if asked about it. But this is still permissive—the court “may” require disclosure.
Can a lay or expert witness give an opinion on the “ultimate issue” in a case?
Yes, UNLESS:
(1) The opinion is a legal conclusion (e.g., insanity, testamentary capacity, negligence, etc.), or
(2) IN CRIMINAL CASE, the opinion is about the defendant’s mental state or condition that constitutes an element of the crime or defense. “Those matters are for the trier of fact alone.”
May an expert’s opinion be admitted if the underlying facts or data are inadmissible?
YES, IF experts in the field would reasonably rely on those same bases.
May the underlying facts or data of an expert opinion be disclosed to the jury even if the facts or data are by themselves inadmissible?
YES IF the “probative value in helping the jury evaluate the opinion substantially outweighs prejudicial effect”
(basically 403+ balancing for “helpfulness”)
What are the requirements for challenging an expert’s testimony with a learned treatise?
The treatise must be admitted as substantive evidence, so follow the hearsay exception steps: must come in through an expert, and must be established as an authoritative source.
So, if bringing in on cross-examination, ask the witness if they’re familiar with the source and recognize it as authoritative—if yes, then good to go; if not, then bring it in through your own witness.
