Rule 701. Opinion Testimony by Lay Witnesses
Rule 702. Testimony by Experts
Rule 703. Bases of Opinion Testimony by Experts
Rule 704. Opinion on Ultimate Issue
Rule 705. Disclosure of Facts or Data Underlying Expert Opinion
720. Expert Witness
721. Expert Witness Cross-Examination
722. Court Appointment; Compensation to Expert
723. Limiting Expert Witnesses
801. Expert Witness Testimony
802. Expert Witness May Testify about Basis for Testimony
803. Court May Exclude Testimony
804. Testimony Based on Anotherís Opinion
805. Opinion on Ultimate Issue
Federal Rules of
If the witness is not testifying as an expert, the
witness testimony in the form of opinions or inferences is limited to
those opinions or inferences which are (a) rationally based on the
perception of the witness, and (b) helpful to a clear understanding of the
witness' testimony or the determination of a fact in issue, and (c) not
based on scientific, technical, or other specialized knowledge within the
Rule 702 .
If scientific, technical, or other specialized knowledge
will assist the trier of fact to understand the evidence or to determine a
fact in issue, a witness qualified as an expert by knowledge, skill,
experience, training, or education, may testify thereto in the form of an
opinion or otherwise, if (1) the testimony is based upon sufficient facts
or data, (2) the testimony is the product of reliable principles and
methods, and (3) the witness has applied the principles and methods
reliably to the facts of the case.
The facts or data in the particular case upon which an
expert bases an opinion or inference may be those perceived by or made
known to the expert at or before the hearing. If of a type reasonably
relied upon by experts in the particular field in forming opinions or
inferences upon the subject, the facts or data need not be admissible in
evidence in order for the opinion or inference to be admitted. Facts or
data that are otherwise inadmissible shall not be disclosed to the jury by
the proponent of the opinion or inference unless the court determines that
their probative value in assisting the jury to evaluate the expert's
opinion substantially outweighs their prejudicial effect.
(a) Except as provided in subdivision (b), 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.
(b) No expert witness testifying with respect to the
mental state or condition of a defendant in a criminal case may state an
opinion or inference as to whether the defendant did or did not have the
mental state or condition constituting an element of the crime charged or
of a defense thereto. Such ultimate issues are matters for the trier of
The expert may testify in terms of opinion or inference
and give reasons therefor without first testifying to the underlying facts
or data, unless the court requires otherwise. The expert may in any event
be required to disclose the underlying facts or data on cross-examination.
California Evidence Code
720. Expert Witness
(a) A person is qualified to testify
as an expert if he has special knowledge, skill, experience, training, or
education sufficient to qualify him as an expert on the subject to which
his testimony relates. Against the objection of a party, such special
knowledge, skill, experience, training, or education must be shown before
the witness may testify as an expert.
(b) A witness' special knowledge,
skill, experience, training, or education may be shown by any otherwise
admissible evidence, including his own testimony.
721. Expert Witness
(a) Subject to subdivision (b), a
witness testifying as an expert may be cross-examined to the same extent
as any other witness and, in addition, may be fully cross-examined as to
(1) his or her qualifications, (2) the subject to which his or her expert
testimony relates, and (3) the matter upon which his or her opinion is
based and the reasons for his or her opinion.
(b) If a witness testifying as an
expert testifies in the form of an opinion, he or she may not be
cross-examined in regard to the content or tenor of any scientific,
technical, or professional text, treatise, journal, or similar publication
unless any of the following occurs:
(1) The witness referred to,
considered, or relied upon such publication in arriving at or forming his
or her opinion.
(2) The publication has been
admitted in evidence.
(3) The publication has been
established as a reliable authority or admission of the witness or by
other expert testimony or by judicial notice.
If admitted, relevant
portions of the publication may be read into evidence but may not be
received as exhibits.
Appointment; Compensation to Expert
(a) The fact of the appointment of an
expert witness by the court may be revealed to the trier of fact.
(b) The compensation and expenses paid
or to be paid to an expert witness by the party calling him is a proper
subject of inquiry by any adverse party as relevant to the credibility of
the witness and the weight of his testimony.
Limiting Expert Witnesses
The court may, at any time before or
during the trial of an action, limit the number of expert witnesses to be
called by any party.
801. Expert Witness
If a witness is testifying as an
expert, his testimony in the form of an opinion is limited to such an
opinion as is:
(a) Related to a subject that
is sufficiently beyond common experience that the opinion of an expert
would assist the trier of fact; and
(b) Based on matter
(including his special knowledge, skill, experience, training, and
education) perceived by or personally known to the witness or made known
to him at or before the hearing, whether or not admissible, that is of
a type that reasonably may be relied upon by an expert in forming an
opinion upon the subject to which his testimony relates, unless an expert
is precluded by law from using such matter as a basis for his opinion.
802. Expert Witness
May Testify about Basis for Testimony
A witness testifying in the form of an
opinion may state on direct examination the reasons for his opinion and
the matter (including, in the case of an expert, his special knowledge,
skill, experience, training, and education) upon which it is based, unless
he is precluded by law from using such reasons or matter as a basis for
his opinion. The court in its discretion may require that a witness
before testifying in the form of an opinion be first examined concerning
the matter upon which his opinion is based.
Court May Exclude Testimony
The court may, and upon objection
shall, exclude testimony in the form of an opinion that is based in whole
or in significant part on matter that is not a proper basis for such an
opinion. In such
case, the witness may, if there
remains a proper basis for his opinion, then state his opinion after
excluding from consideration the matter determined to be improper.
Testimony Based on Anotherís Opinion
(a) If a witness testifying as an
expert testifies that his opinion is based in whole or in part upon the
opinion or statement of another person, such other person may be called
and examined by any adverse party as if under cross-examination concerning
the opinion or statement.
(b) This section is not applicable if
the person upon whose opinion or statement the expert witness has relied
is (1) a party, (2) a person identified with a party within the meaning of
subdivision (d) of Section 776, or (3) a witness who has testified in the
action concerning the subject matter of the opinion or statement upon
which the expert witness has relied.
(c) Nothing in this section makes
admissible an expert opinion that is inadmissible because it is based in
whole or in part on the opinion or statement of another person.
(d) An expert opinion otherwise
admissible is not made inadmissible by this section because it is based on
the opinion or statement of a person who is unavailable for examination
pursuant to this section.
805. Opinion on
Testimony in the form of an opinion
that is otherwise admissible is not objectionable because it embraces the
ultimate issue to be decided by the trier of fact.