Form of the Opinion
- The foundation consists of no more than determining that the witness has formed an opinion, and of what that opinion consists.
- Rule 704.
Rule 704. Opinion on Ultimate Issue Testimony in the form of an opinion or inference otherwise admissible is not objectionable because it embraces an ultimate issue to be decided by the trier of fact.
- The current standard is whether the testimony assists the trier of fact, not whether it embraces an “ultimate issue” so as to usurp the panel’s function. At the same time, ultimate-issue opinion testimony is not automatically admissible. Opinion must be relevant and helpful as determined through Rules 401-403 and 702.
- In United States v. Diaz, 59 M.J. 79 (2003), the CAAF held that it was
improper for an expert to testify that the death of appellant’s child was a
homicide and that the appellant was the perpetrator, when the cause of
death and identity of the perpetrator were the primary issues at trial.
- One recurring problem is that an expert should not opine that a certain
witness’s rendition of events is believable or not. See, e.g., United States
v. Petersen, 24 M.J. 283, 284 (C.M.A. 1987) (“We are skeptical about
whether any witness could be qualified to opine as to the credibility of
another.”) The expert may not become a “human lie detector.” United
States v. Palmer, 33 M.J. 7, 12 (C.M.A. 1991); see also United States v.
Brooks, 64 M.J. 325 (2007) (discussing that in a child sexual abuse case,
where the government expert’s testimony suggested that there was better
than a ninety-eight percent probability that the victim was telling the
truth, such testimony was the functional equivalent of vouching for the
credibility or truthfulness of the victim, and implicates the very concerns
underlying the prohibition against human lie detector testimony.
- Questions such as whether the expert believes the victim was
raped, or whether the victim is telling the truth when she claimed
to have been raped (i.e. was the witness truthful?) are
- However, the expert may opine that a victim’s testimony or
history is consistent with what the expert’s examination found,
and whether the behavior at issue is typical of victims of such
crimes. Focus on symptoms, not conclusions concerning
veracity. See United States v. Birdsall, 47 M.J. 404 (1998)
(expert’s focus should be on whether children exhibit behavior
and symptoms consistent with abuse; reversible error to allow
social worker and doctor to testify that the child-victims were
telling the truth and were the victims of sexual abuse). Example:
An expert may testify as to what symptoms are found among
children who have suffered sexual abuse and whether the childwitness
has exhibited these symptoms. United States v.
Harrison, 31 M.J. 330, 332 (C.M.A. 1990).