Copyright © 2010

Thomson Reuters

Chapter 7

EXPERT TESTIMONY

Table of Sections

Sec.

7.00 Introduction.

7.01 Expert Opinion: Convergence.

7.02 Expert Opinion: Divergence.

7.03 The Federal Approach.

7.04 Daubert and California.

7.05 Cross–Examining Experts.

7.06 Court Appointed Experts.

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§ 7.00 Introduction

FEDERAL RULES OF EVIDENCE

RULE 701. OPINION TESTIMONY BY LAY WITNESSES

Rule 701. Opinion Testimony by Lay Witnesses

If a witness is not testifying as an expert, testimony in the form of an opinion is limited to one that is:

(a) rationally based on the witness's perception;

(b) helpful to clearly understanding the witness's testimony or to determining a fact in issue; and

(c) not based on scientific, technical, or other specialized knowledge within the scope of Rule 702..

Rule 702. Testimony by Expert Witnesses

A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:

(a) the expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;

(b) the testimony is based on sufficient facts or data;

(c) the testimony is the product of reliable principles and methods; and

(d) the expert has reliably applied the principles and methods to the facts of the case.

Rule 703. Bases of an Expert's Opinion Testimony

An expert may base an opinion on facts or data in the case that the expert has been made aware of or personally observed. If experts in the particular field would reasonably rely on those kinds of facts or data in forming an opinion on the subject, they need not be admissible for the opinion to be admitted. But if the facts or data would otherwise be inadmissible, the proponent of the opinion may disclose them to the jury only if their probative value in helping the jury evaluate the opinion substantially outweighs their prejudicial effect.

Rule 704. Opinion on an Ultimate Issue

(a) In General--Not Automatically Objectionable. An opinion is not objectionable just because it embraces an ultimate issue.

(b) Exception. In a criminal case, an expert witness must not state an opinion about whether the defendant did or did not have a mental state or condition that constitutes an element of the crime charged or of a defense. Those matters are for the trier of fact alone.

Rule 705. Disclosing the Facts or Data Underlying an Expert's Opinion

Unless the court orders otherwise, an expert may state an opinion--and give the reasons for it--without first testifying to the underlying facts or data. But the expert may be required to disclose those facts or data on cross- examination.

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CALIFORNIA EVIDENCE CODE

§ 720. Qualification as an 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.

§ 723. Limit on number of 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.

§ 800. Lay witnesses; opinion testimony

If a witness is not testifying as an expert, his testimony in the form of an opinion is limited to such an opinion as is permitted by law, including but not limited to an opinion that is:

(a) Rationally based on the perception of the witness; and

(b) Helpful to a clear understanding of his testimony.

§ 801. Expert witnesses; opinion testimony

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. Statement of basis of opinion

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.

§ 803. Opinion based on improper matter

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.

§ 804. Opinion based on opinion or statement of another

(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 ultimate issue

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.

§ 870. Opinion as to sanity

A witness may state his opinion as to the sanity of a person when:

(a) The witness is an intimate acquaintance of the person whose sanity is in question;

(b) The witness was a subscribing witness to a writing, the validity of which is in dispute, signed by the person whose sanity is in question and the opinion relates to the sanity of such person at the time the writing was signed; or

(c) The witness is qualified under Section 800 or 801 to testify in the form of an opinion.

§ 1107. Intimate partner battering and its effects; expert testimony in criminal actions; sufficiency of foundation; abuse and domestic violence; applicability to Penal Code; impact on decisional law

(a) In a criminal action, expert testimony is admissible by either the prosecution or the defense regarding intimate partner battering and its effects, including the nature and effect of physical, emotional, or mental abuse on the beliefs, perceptions, or behavior of victims of domestic violence, except when offered against a criminal defendant to prove the occurrence of the act or acts of abuse which form the basis of the criminal charge.

(b) The foundation shall be sufficient for admission of this expert testimony if the proponent of the evidence establishes its relevancy and the proper qualifications of the expert witness. Expert opinion testimony on intimate partner battering and its effects shall not be considered a new scientific technique whose reliability is unproven.

(c) For purposes of this section, "abuse" is defined in Section 6203 of the Family Code, and "domestic violence" is defined in Section 6211 of the Family Code and may include acts defined in Section 242, subdivision (e) of Section 243, Section 262, 273.5, 273.6, 422, or 653m of the Penal Code.

(d) This section is intended as a rule of evidence only and no substantive change affecting the Penal Code is intended.

(e) This section shall be known, and may be cited, as the Expert Witness Testimony on Intimate Partner Battering and Its Effects Section of the Evidence Code.

(f) The changes in this section that become effective on January 1, 2005, are not intended to impact any existing decisional law regarding this section, and that decisional law should apply equally to this section as it refers to "intimate partner battering and its effects" in place of "battered women's syndrome."

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Comparative Note. The rules of evidence recognize that occasionally jurors need expert help in resolving important factual issues. The California Evidence Code and the Federal Rules of Evidence have responded by replacing restrictive Common Law rules with a generous approach that generally allows experts to present to jurors the same kind of information experts use and rely upon in their respective fields.

A generous approach to the admissibility of expert testimony, however, has not eliminated the role of the trial judge. Although the power of California judges to withhold expert testimony from the jurors differs from the power exercised by federal judges, both have the power to sustain objections to expert testimony. Opponents may object to the need for the expert testimony as well as to the qualifications of the expert to provide the evidence. In addition, opponents may object to a particular opinion on the ground that it is based on inappropriate matter as determined by experts in the field. They may also contest the validity of the principles and the propriety of the methods employed by the witness in reaching the expert opinion.

§ 7.01 Expert Opinion: Convergence

Comparative Note. When the Federal Rules of Evidence were first adopted in 1975, the federal approach to the admissibility of expert opinion was remarkably similar to that of the Evidence Code. To appreciate the changes introduced by the Code and the Rules, it is important to focus first on why the Common Law allowed expert testimony in the first place.

The Common Law recognized that the triers of fact, whether judges or jurors, were sometimes incapable of drawing a necessary inference from the evidence. If the issue, for example, was whether the plaintiff's injury was permanent, the fact finder might not have the training or experience needed to determine that issue from the testimony of percipient witnesses, such as the plaintiff's account of the effects of the injury.

One way to remedy this deficiency was to have a qualified medical expert present in the court room during the examination of the plaintiff and other witnesses called to describe the plaintiff's injuries. The expert would then be called to draw the needed inference from the evidence in the form of an opinion. Convenience gave way to the use of the hypothetical question. No longer was it necessary to have the expert sit in court. Instead, the calling party could supply the critical parts of the percipient witnesses' testimony to the expert in a question in which the calling party asked the expert to assume the existence of the facts supplied by the percipient witnesses.

First the Code and then the Rules introduced a radical change to the use of expert opinion by allowing an expert to offer an opinion that was not necessarily based on the evidence introduced at the trial (§ 801(b), Rule 703). Moreover, both permitted the use of the expert's opinion even if it was based on matter that was inadmissible. What matters under the Code and the Rules is that the data used by the expert be of the type reasonably relied upon by experts in the field. Permitting experts to base opinions on matter reasonably relied upon by experts in the field conformed evidentiary practice with the customs and practices of experts themselves. Thus, if sound medical practices allow doctors to reach important health decisions on information provided by patients and specialists, then those decisions should be sufficiently reliable for use in court even if the information provided by the patients and specialists is not admissible.

The use of inadmissible information to support an expert opinion introduced a new danger: the risk that fact finders might use inadmissible matter for an improper purpose. It might be sound medical practice for a doctor to use a radiologist's report in determining whether the plaintiff's injury is permanent. But over a hearsay objection, it would be improper for the jurors to consider the radiologist's report for the truth of the matter asserted unless the report has been received in evidence.

In California the opposing party may object on hearsay (and other) grounds to the doctor's disclosure of the radiologist's finding. If the judge sustains the hearsay objection but concludes that the probative value of disclosing the finding is not substantially outweighed by its prejudicial effects, the judge may allow the jury to hear the evidence subject to a limiting instruction charging them not to consider the finding for the truth of the matter stated. Because of doubts about whether jurors can abide by this instruction, Federal Rule 703 prohibits the disclosure of inadmissible facts or data to the jurors unless the judge determines that their probative value in assisting the jurors evaluate the expert's opinion substantially outweighs their prejudicial effects.

Rule 703 offers the opposing party greater protection than does the Code. Under Rule 703's special balancing provision, the judge may not allow the proponent to disclose the inadmissible matter unless the judge finds that the evaluative value of the evidence substantially outweighs its prejudicial effects. Under the California approach, the general balancing rule embodied in Evidence Code § 352 reverses the balance. It requires the judge to allow disclosure of the inadmissible matter unless its evaluative value is substantially outweighed by its prejudicial effects.

Other federal provisions governing the use of expert opinion virtually mirror the provisions found in the Code. Rule 702 and § 801(b) recognize that for expert opinion to be received the fact finders do not have to be wholly ignorant of the subject to which the expert testimony is directed. It is enough under Rule 702 and § 801(b) if the expert opinion assists the fact finders understand evidence or determine an issue that is beyond their common experience. Rule 702 and § 720 provide that an expert may be qualified on the basis of knowledge, skill, experience, training, or education, including the expert's own testimony. Both allow the use of opinions that are otherwise admissible even if they embrace ultimate issues (Rule 704(a), § 805). And both permit experts to give their opinions without first disclosing the basis of their opinions, unless the judge requires otherwise (Rule 705, § 805).

California has some special provisions. One addresses the admissibility of expert opinions based on other opinions. Section 804 makes clear that an expert opinion can be based in whole or in part on opinions by others, even if the other persons are unavailable for examination. But if those persons are available, the adverse party may call and examine them as if under cross-examination concerning their opinions. Nothing in the Rules prohibits the adverse party from calling and examining these witnesses or prohibits the use of opinions based on opinions by individuals who are unavailable for examination. Under the Code and probably under the Rules, the admissibility of expert testimony based on opinions by others depends initially on whether those opinions are of the type reasonably relied upon by experts in the field in reaching their conclusions.

California has a number of provisions governing opinion evidence regarding the value, damages, and benefits in eminent domain and inverse condemnation cases (§§ 810–824). California also has special provisions on the use of lay and expert opinion on the question of sanity (§ 870).

Of particular importance in criminal cases, California has a provision authorizing the use of expert testimony to prove battered women's syndrome, including to explain why a woman suffering from the syndrome perceived a need to kill in self-defense (§ 1107). The provision is designed to end controversy regarding the admissibility of battered women's syndrome.

Rule 704(b) prohibits an expert from giving an opinion on whether the accused did or did not have a mental state constituting an element of the offense charged or a defense thereto. This provision was added by Congress in 1984. Earlier that year, the California Legislature added a similar provision to the Penal Code prohibiting an expert from testifying about whether an accused's mental illness, disorder, or defect precluded the accused from forming the mental state of the offense charged (Penal Code § 29). Although the California provision is narrower, in both jurisdictions, only the trier of fact is allowed to deduce whether the accused entertained the requisite mental state.

§ 7.02 Expert Opinion: Divergence

Comparative Note. The Code and the Rules, as interpreted, differ on the role the judge should play in excluding some forms of unreliable expert testimony. Although the Code and the Rules began with similar provisions, judicial construction of the California and federal provisions has led to a divergence in the judge's role.

California—The General Rule. Expert opinion will not help fact finders understand evidence or resolve issues beyond their competence unless the expert is qualified to provide them with the help they need. Whether an expert is qualified to provide the needed help is determined under California Evidence Code § 405. This provision is designed to withhold evidence from the jurors that is unreliable. Combined with other provisions, § 405 requires the party calling the expert to persuade the judge by a preponderance of the evidence that the expert is qualified to render the needed assistance.1

An opinion even by a qualified expert will not help the fact finders unless it is validly drawn from appropriate data. Section 801attempts to exclude unreliable opinions by limiting experts to those opinions based on matter "that is of the type that reasonably may be relied upon" by experts in the field.

Moreover, the question whether required protocols or methodologies have been followed also should be governed by § 405. The failure to follow correct procedures can result in invalid conclusions even if the expert is qualified to draw the conclusion and used appropriate data. Accordingly, over objection the calling party should persuade the judge by a preponderance of the evidence that the expert followed the required protocols and methodologies in reaching the opinion.

The inadmissibility of expert opinions based on improper matter is reinforced in California by another rule. On its own motion or upon objection, § 803 requires a judge to "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."

California—A Special Rule. When the expert opinion is based on novel scientific principles or techniques, the California courts use the Kelly test to determine the admissibility of the opinion. Adopting the approach taken in Frye v. United States,2 the California Supreme Court held in People v. Kelly3 that the proponent must persuade the judge that the novel scientific principle or technique " 'has been sufficiently established to have gained general acceptance in the particular field in which it belongs.' "4

To help guide the bench and bar apply the Kelly test, the court set down two guidelines. First, the court emphasized that Kelly is limited "to that class of expert testimony which is based, in whole or in part, on a technique, process, or theory which is new to science and, even more so, the law."5

Second, the court underscored that Kelly should be applied to expert evidence that carries a "misleading aura of scientific infallibility"6 and thus might mislead the jurors.

If Kelly applies, the proponent must persuade the judge that the scientific principles or techniques underlying the expert testimony meet the general acceptance test. Moreover, if the expert testimony is predicated on the application of specific protocols or methodologies, the proponent must satisfy the judge that the correct procedures were followed.

§ 7.03 The Federal Approach

Comparative Note. In Daubert v. Merrell Dow Pharmaceuticals, Inc.1 the U.S. Supreme Court defined the role of federal judges in screening expert testimony. Noting sharp divisions among the circuits on the proper standards for admitting expert testimony, the Court held that under the Federal Rules of Evidence federal trial judges must ensure "that any and all scientific testimony or evidence is not only relevant, but reliable."2

The Court laid down four nonexclusive guidelines to help federal judges assess the evidence's scientific validity. A judge should consider whether the evidence is based on theories or techniques that can be or have been tested.3 A judge should also consider whether the theory or technique has been subjected to peer review and publication.4 A judge should consider the known or potential rate of error as well as the existence and maintenance of standards controlling a technique's operation.5 Finally, a judge should consider whether the techniques or theories employed have been generally accepted or rejected by the pertinent scientific community.6 Though a finding that the proffered evidence is scientifically valid does not require that the techniques or theories supporting it be generally accepted, widespread acceptance or rejection "can be an important factor" in ruling the evidence admissible.7

Daubert is not limited to scientific evidence despite its emphasis on "scientific testimony". In Kumho Tire Co. Ltd. v. Carmichael8 the United States Supreme Court held that the federal judiciary's obligation to ensure that all scientific testimony is not only relevant but reliable extends to all "expert" testimony.9

In response to Daubert and Kumho, Federal Rule of Evidence 702 was amended in 2000. It now calls for the exclusion of expert opinion based on scientific, technical or other specialized knowledge unless the judge finds that "(b) the testimony is based on sufficient facts or data; (c) the testimony is the product of reliable principles and methods; and (d) the expert has reliably applied the principles and methods to the facts of the case." The accompanying Advisory Committee Note states that the "standards set forth in the amendment are broad enough to require consideration of any or all of the specific Daubert factors where appropriate." The Note also makes clear that under the amended rule the proponent must establish the admissibility requirements of expert testimony and other scientific evidence by a preponderance of the evidence.

§ 7.04 Daubert and California

Comparative Note. In People v. Leahy1 the California Supreme Court declined to adopt Daubert as the standard to be used to determine the admissibility of expert testimony in California. Instead, the court chose to adhere to the Kelly test.2

California's rejection of Daubert should not be overstated, however. Kelly is of limited application. California judges are required to apply Kelly only when the admissibility of an expert's opinion is challenged on the ground that it is based on novel scientific principles or techniques that lack the required acceptance by experts in the field. Still, a California judge's screening role can differ sharply from a federal judge's when Kelly does apply. While Daubert forces federal judges to determine the scientific validity of all expert testimony grounded in science, Kelly merely requires California judges to determine whether the contested principle or technique has been accepted as reliable by the relevant scientific community. The role of the California judge under Kelly is not to determine reliability as a scientific matter but only whether the relevant scientific community has reached the prescribed consensus.

California judges do play a role similar to that of federal judges when expert opinion is challenged on non-Kelly grounds. Over objection the proponent must still persuade the judge by preponderance of the evidence that (1) the expert's opinion is based on the type of matter relied upon by experts in the field and (2) the expert followed accepted protocols or methodologies in reaching his or her opinion. Opinions based on matter experts would ignore or on incorrect procedures are unlikely to produce valid conclusions. Accordingly, ruling on these objections requires California judges to assess the scientific validity of the proffered opinion.

§ 7.05 Cross–Examining Experts

FEDERAL RULES OF EVIDENCE

Rule 803. Exceptions to the Rule Against Hearsay--Regardless of Whether the Declarant Is Available as a Witness

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(18) Statements in Learned Treatises, Periodicals, or Pamphlets. A statement contained in a treatise, periodical, or pamphlet if:

(A) the statement is called to the attention of an expert witness on cross-examination or relied on by the expert on direct examination; and

(B) the publication is established as a reliable authority by the expert's admission or testimony, by another expert's testimony, or by judicial notice.

If admitted, the statement may be read into evidence but not received as an exhibit.

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CALIFORNIA EVIDENCE CODE

§ 721. Cross-examination of 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 by the testimony 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.

§ 722. Credibility of expert witness

(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.

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Comparative Note.

California. The Evidence Code has a number of provisions regulating the cross-examination of expert witnesses. Section 721(a) is a general provision that allows the adverse party to cross examine an expert to the same extent as any other witness, including the expert's qualifications, the subject to which the expert's testimony relates, the matter upon which the expert's opinion is based, and the reasons for the expert's opinion. Section 722(b) allows the adverse party to question an expert about the compensation and expenses the calling party paid or will pay to the expert. The Federal Rules do not have specific provisions on these matters, but all are within the federal definition of relevant matter, since under Rules 401 and 402 evidence relating to the credibility of witnesses is of consequence to the determination of the action.

Evidence Code § 721(b), but not the Rules, prohibits cross examining an expert "in regard to the content or tenor of any scientific, technical, or professional text, treatise, journal, or similar publication unless * * * (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, or (3) the publication has been established as reliable authority by the testimony or admission of the witness or by other expert testimony or by judicial notice."

The prohibition is designed to bar the cross-examiner from bringing before the fact finder the opinion of absentee authors without the safeguard of cross-examination. The California Supreme Court, however, has ignored § 721(b)'s prohibition on crossing experts on treatises they did not consider. According to the court, "[A] party seeking to attack the credibility of [an] expert may bring to the attention of the jury material relevant to the issue on which the expert has offered an opinion [and] of which the expert was unaware or which he did not consider."1

Federal Rules. Rule 803(18) is more generous than the Code with respect to the cross-examination of experts. First, as the Advisory Committee Note makes clear, the cross examiner is allowed to inquire about statements in treatises, irrespective of whether the expert relied on them or considers them authoritative. Rule 803(18) is designed to avoid "the possibility that the expert may at the outset block cross-examination by refusing to concede reliance or authoritativeness." (Advisory Committee Note). Second, Rule 803 (18) provides that the statements may be admitted for the truth of the matter asserted if (1) the statements are established as reliable authority by expert testimony or judicial notice and (2) the treatise was relied upon by an expert witness on direct examination or was called to the expert's attention on cross-examination. Thus, when a treatise has been established as authoritative, appropriate passages may be read in evidence, so long as an expert is on the stand and available to explain and assist in applying the treatise (Advisory Committee Note).

§ 7.06 Court Appointed Experts

FEDERAL RULES OF EVIDENCE

Rule 706. Court-Appointed Expert Witnesses

(a) Appointment Process. On a party's motion or on its own, the court may order the parties to show cause why expert witnesses should not be appointed and may ask the parties to submit nominations. The court may appoint any expert that the parties agree on and any of its own choosing. But the court may only appoint someone who consents to act.

(b) Expert's Role. The court must inform the expert of the expert's duties. The court may do so in writing and have a copy filed with the clerk or may do so orally at a conference in which the parties have an opportunity to participate. The expert:

(1) must advise the parties of any findings the expert makes;

(2) may be deposed by any party;

(3) may be called to testify by the court or any party; and

(4) may be cross-examined by any party, including the party that called the expert.

(c) Compensation. The expert is entitled to a reasonable compensation, as set by the court. The compensation is payable as follows:

(1) in a criminal case or in a civil case involving just compensation under the Fifth Amendment, from any funds that are provided by law; and

(2) in any other civil case, by the parties in the proportion and at the time that the court directs--and the compensation is then charged like other costs.

(d) Disclosing the Appointment to the Jury. The court may authorize disclosure to the jury that the court appointed the expert.

(e) Parties' Choice of Their Own Experts. This rule does not limit a party in calling its own experts.

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CALIFORNIA EVIDENCE CODE

§ 730. Appointment of expert by court

When it appears to the court, at any time before or during the trial of an action, that expert evidence is or may be required by the court or by any party to the action, the court on its own motion or on motion of any party may appoint one or more experts to investigate, to render a report as may be ordered by the court, and to testify as an expert at the trial of the action relative to the fact or matter as to which the expert evidence is or may be required. The court may fix the compensation for these services, if any, rendered by any person appointed under this section, in addition to any service as a witness, at the amount as seems reasonable to the court.

Nothing in this section shall be construed to permit a person to perform any act for which a license is required unless the person holds the appropriate license to lawfully perform that act.

§ 731. Payment of court-appointed expert

(a) In all criminal actions and juvenile court proceedings, the compensation fixed under Section 730 shall be a charge against the county in which such action or proceeding is pending and shall be paid out of the treasury of such county on order of the court.

(b) In any county in which the board of supervisors so provides, the compensation fixed under Section 730 for medical experts in civil actions in such county shall be a charge against and paid out of the treasury of such county on order of the court.

(c) Except as otherwise provided in this section, in all civil actions, the compensation fixed under Section 730 shall, in the first instance, be apportioned and charged to the several parties in such proportion as the court may determine and may thereafter be taxed and allowed in like manner as other costs.

§ 732. Calling and examining court-appointed expert

Any expert appointed by the court under Section 730 may be called and examined by the court or by any party to the action. When such witness is called and examined by the court, the parties have the same right as is expressed in Section 775 to cross-examine the witness and to object to the questions asked and the evidence adduced.

§ 733. Right to produce other expert evidence

Nothing contained in this article shall be deemed or construed to prevent any party to any action from producing other expert evidence on the same fact or matter mentioned in Section 730; but, where other expert witnesses are called by a party to the action, their fees shall be paid by the party calling them and only ordinary witness fees shall be taxed as costs in the action.

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Comparative Note. Rule 706 and Code § 730 allow judges to appoint experts on their own or a party's motion if in the judge's discretion expert assistance is necessary. Section 730 authorizes judges to appoint experts to investigate and report as well as to testify. Rule 706 is not as specific; it simply requires the judge to inform the experts of their duties. Experts appointed by federal judges, however, are required to inform the parties of their findings, if any (Rule 706). The Code is silent on this point, but nothing in the Code precludes a California judge from ordering court appointed experts to disclose their findings to the parties.

Rule 706 expressly allows the parties to depose a court appointed expert. The Code does not contain an equivalent provision.1

Rule 706(b) and Code § 731(c) empower the judge to fix the compensation to be paid to court appointed experts and, in civil actions, to apportion the compensation among the parties.

Rule 706(a) allows each party (including the calling party) to cross-examine a court appointed expert. In California, each party may cross-examine the court appointed expert if the court calls and examines the expert (§ 732). But if a party calls the court appointed expert, the calling party may not examine the expert as if on cross-examination.

Both the Code and the Rules allow the judge to inform the jurors of the fact that an expert witness was appointed by the court (Rule 706 (c), § 722). In both jurisdictions, the calling of court appointed experts does not preclude the parties from calling their own experts to testify on the same matters (Rule 706(d), § 733).