Code Details

Evidence Code – EVID
DIVISION 6. WITNESSES [700 – 795] ( Division 6 enacted by Stats. 1965, Ch. 299. )
CHAPTER 3. Expert Witnesses [720 – 733] ( Chapter 3 enacted by Stats. 1965, Ch. 299. )

ARTICLE 1. Expert Witnesses Generally [720 – 723] ( Article 1 enacted by Stats. 1965, Ch. 299. )

Exact Statute Text

(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.

(Amended by Stats. 1997, Ch. 892, Sec. 11. Effective January 1, 1998.)

Evidence Code § 721 Summary

California Evidence Code § 721 outlines the specific rules governing the cross-examination of expert witnesses in a legal proceeding. This statute ensures that expert testimony, which often carries significant weight, can be thoroughly scrutinized.

Subsection (a) establishes that an expert witness can be cross-examined like any other witness. Crucially, it also allows for additional, extensive cross-examination specifically on three key areas:
1. The expert’s qualifications: Their education, experience, licenses, and other credentials that qualify them to offer an opinion.
2. The subject of their testimony: The specific field or topic their expert opinion addresses.
3. The basis and reasons for their opinion: The facts, data, scientific principles, and methodology the expert used to form their conclusion.

Subsection (b) places important limitations on the use of scientific, technical, or professional publications (like texts, journals, or treatises) during the cross-examination of an expert. An expert cannot be cross-examined using such a publication unless one of the following conditions is met:
1. The expert witness explicitly referred to, considered, or relied upon that specific publication when forming their opinion.
2. The publication has already been formally admitted into evidence by the court.
3. The publication has been established as a reliable authority, either through the expert’s own testimony or admission, by another expert’s testimony, or by the court taking judicial notice of its reliability.

If a publication meets these criteria and is admitted for cross-examination, only the relevant portions can be read into the record; the entire publication itself generally cannot be entered as a physical exhibit.

### Evidence Code § 721 Purpose

The primary purpose of California Evidence Code § 721 is to safeguard the integrity and reliability of expert testimony in legal proceedings. Expert witnesses provide opinions that can significantly influence the outcome of a case, often on complex scientific, technical, or medical matters beyond the understanding of the average layperson or juror.

This statute serves several critical functions:

• Ensuring Thorough Scrutiny: By allowing extensive cross-examination on qualifications, the subject matter, and the basis for an opinion, the law ensures that an expert’s credibility, methodology, and the foundation of their conclusions are rigorously tested. This helps prevent “junk science” or unsubstantiated opinions from swaying a jury.
• Promoting Fairness: Subdivision (b) is designed to prevent unfair “ambush” tactics. Without this limitation, a cross-examining attorney could introduce obscure or non-authoritative publications that an expert never considered, potentially misleading the jury or unfairly discrediting a well-founded opinion.
• Maintaining Evidentiary Standards: It ensures that only genuinely relevant and authoritative publications are used to challenge an expert, upholding the court’s role in controlling the quality of evidence presented.
• Aiding Truth-Finding: Ultimately, the statute aims to assist the court and jury in evaluating the weight and validity of expert opinions, leading to more just and informed decisions. It balances the need for robust advocacy with the fundamental goal of truth-finding in the legal system.

### Evidence Code § 721 Real-World Example

Imagine a personal injury lawsuit stemming from a slip-and-fall accident at a grocery store. The plaintiff claims a severe back injury requiring extensive treatment and future care.

Plaintiff’s Expert Witness: The plaintiff calls Dr. Emily Chen, an orthopedic surgeon, to testify about the nature and extent of the plaintiff’s back injury, its causation by the fall, and the projected cost of future medical care.

Defense Cross-Examination (Applying § 721(a)):

• Qualifications (a)(1): The defense attorney, Mr. Davis, begins by asking Dr. Chen about her board certifications, how many similar cases she has treated, and any disciplinary actions against her. He might probe if her specialty directly aligns with the specific type of spinal injury alleged.
• Subject of Testimony (a)(2): Mr. Davis then questions Dr. Chen on the specific diagnostic criteria she used to determine the injury and the generally accepted medical understanding of those criteria.
• Basis and Reasons for Opinion (a)(3): Mr. Davis challenges the doctor’s reliance on specific MRI reports, asking if she considered other potential causes for the back pain (e.g., pre-existing conditions). He asks why she chose a particular treatment plan over others and the scientific literature supporting her prognosis and cost estimates.

Defense Use of Publications (Applying § 721(b)):
Mr. Davis wants to introduce a specific article from the “Journal of Orthopedic Medicine” that suggests a different, less costly treatment protocol for the type of injury the plaintiff sustained.

• Scenario 1 (Permitted): Mr. Davis asks, “Dr. Chen, in forming your opinion, did you consider the recent article by Dr. Smith in the ‘Journal of Orthopedic Medicine’ from last year, which suggests conservative treatment for this specific condition?” If Dr. Chen replies, “Yes, I did review that article, but I found its methodology flawed for this particular patient,” then Mr. Davis can proceed to cross-examine her about the article’s content, as she “referred to, considered, or relied upon” it.
• Scenario 2 (Permitted): The “Journal of Orthopedic Medicine” article was previously presented to the court and formally admitted as an exhibit during the testimony of another defense expert who established its reliability. In this case, Mr. Davis can use the article for cross-examination because it “has been admitted in evidence.”
• Scenario 3 (Permitted): Mr. Davis asks, “Dr. Chen, do you consider the ‘Journal of Orthopedic Medicine’ to be a reliable and authoritative publication in your field?” If Dr. Chen answers “Yes,” then the publication “has been established as a reliable authority by the testimony or admission of the witness.” Mr. Davis can then use the relevant portions of the article.
• Scenario 4 (Not Permitted): If Dr. Chen states she has never seen the article, and it has not been admitted into evidence, and she does not acknowledge the journal as a reliable authority (or the defense has no other way to establish its authority), then Mr. Davis generally cannot cross-examine her using that specific article under Evidence Code § 721(b).

This example illustrates how the statute allows for robust challenge of an expert’s testimony while providing critical protections against the misuse of scientific literature.

### Evidence Code § 721 Related Statutes

Evidence Code § 721 does not stand alone but operates within a broader framework of rules governing witnesses and expert testimony. Several related statutes are often referenced or applied in conjunction with it:

• Evidence Code § 720 – Qualification of Expert Witness: This statute defines the criteria for a witness to qualify as an expert (special knowledge, skill, experience, training, or education). Section 721(a)(1) directly relates to this by allowing full cross-examination on an expert’s “qualifications.” The defense will often use § 721 to challenge the foundation laid under § 720.
• Evidence Code § 801 – Opinion Testimony by Expert Witness: This code section specifies that an expert’s opinion must be (a) related to a subject sufficiently beyond common experience and (b) based on matter (including the expert’s own knowledge, or hypotheticals) that is of a type reasonably relied upon by experts in their field. Section 721(a)(3) allows cross-examination on “the matter upon which his or her opinion is based and the reasons for his or her opinion,” directly testing compliance with § 801.
• Evidence Code § 802 – Statement of Basis of Opinion: This statute permits an expert to state the reasons for their opinion and the matter (including inadmissible matter, if reasonably relied upon) upon which it is based. Section 721 provides the opposing counsel the opportunity to challenge those very reasons and underlying matter.
• Evidence Code § 803 – Opinion Based on Improper Matter: This section states that an expert’s opinion based in whole or in significant part on matter that is declared by statute or judicial decision to be an improper basis for an opinion shall be excluded. Cross-examination under § 721 can expose such improper bases, leading to a motion to strike or exclude the expert’s testimony under § 803.
• Evidence Code § 773 – Cross-Examination: This general statute governs the scope and manner of cross-examination for all witnesses, allowing for questioning on any matter within the scope of direct examination. Evidence Code § 721 expands upon § 773 by granting *additional* specific areas of inquiry for expert witnesses.

### Evidence Code § 721 Case Law

California courts have frequently interpreted and applied Evidence Code § 721, particularly concerning the use of publications during cross-examination. Here are a couple of notable cases:

• People v. Clark (1993) 5 Cal.4th 950, 1018: In this significant Supreme Court case, the court affirmed the limitations imposed by Evidence Code § 721(b) on the cross-examination of expert witnesses using professional treatises. The court reiterated that such publications can only be used if the expert referred to, considered, or relied upon them, if they were admitted into evidence, or if they were established as reliable authority. This case underscores the importance of the foundational requirements before a publication can be used to impeach an expert. [Link to Google Scholar: People v. Clark (1993) 5 Cal.4th 950]
• People v. Safirstein (1989) 204 Cal.App.3d 410, 417-418: This appellate court decision also delves into the application of Evidence Code § 721(b). The court clarified that the statute restricts the use of treatises on cross-examination to those the expert either considered or relied upon in forming their opinion, or those that have been established as reliable authority. This case reinforces the protective nature of the statute against the improper use of unverified or unconsidered materials to attack an expert’s credibility. [Link to Google Scholar: People v. Safirstein (1989) 204 Cal.App.3d 410]

These cases, among others, demonstrate the judiciary’s commitment to ensuring fair and proper methods of challenging expert testimony while maintaining the integrity of the evidence presented in court.

### Evidence Code § 721 Why It Matters in Personal Injury Litigation

Evidence Code § 721 is a cornerstone statute in California personal injury litigation, profoundly impacting how cases are litigated, experts are selected, and damages are proven or disputed.

For Plaintiffs (and their Attorneys):

• Defending Your Experts: Plaintiff attorneys rely heavily on medical doctors, accident reconstructionists, economists, and vocational rehabilitation experts to establish causation, the extent of injuries, and the value of damages (medical bills, lost wages, pain and suffering). Understanding § 721 is crucial for preparing your own experts for rigorous cross-examination, ensuring they can articulate their qualifications, the scientific basis of their opinions, and the data they relied upon.
• Anticipating Challenges: Knowing the scope of cross-examination allowed helps attorneys anticipate the defense’s strategy and proactively address potential weaknesses or alternative theories that an expert might be questioned about.
• Protecting Expert Testimony: The limitations in § 721(b) are vital for protecting plaintiff experts from being unfairly attacked with obscure or non-authoritative publications that have no bearing on their actual work or field.

For Defendants (and their Attorneys):

• Challenging Plaintiff Experts: Defense attorneys utilize § 721 as a powerful tool to scrutinize the plaintiff’s experts. They will meticulously question qualifications, methodology, and the foundation of opinions to undermine credibility, reduce damages, or even challenge causation. This can involve probing whether an expert’s opinion aligns with generally accepted scientific principles or if they overlooked crucial data.
• Strategic Use of Publications: Defense counsel can strategically use authoritative texts or journals (meeting the criteria of § 721(b)) to highlight inconsistencies, expose an expert’s unfamiliarity with relevant literature, or present alternative, less severe prognoses for injuries.
• Minimizing Damages: By effectively cross-examining plaintiff’s medical and economic experts, defense attorneys can raise doubts about the necessity of expensive treatments, the permanence of injuries, or the true extent of lost earning capacity, ultimately aiming to lower the potential damage award.

Overall Impact on Personal Injury Cases:

• Fairness and Reliability: This statute helps ensure that expert testimony, which often forms the backbone of personal injury claims, is thoroughly vetted and based on sound evidence, not speculation or bias.
• Informed Decisions: By allowing robust cross-examination, § 721 empowers juries and judges to make more informed decisions about complex medical, scientific, or technical issues, leading to more just outcomes.
• Strategic Litigation: Attorneys on both sides must carefully select and prepare their experts, knowing that their testimony will be subject to intense scrutiny under the guidelines of § 721. It shapes discovery, deposition strategy, and trial advocacy, making expert witness management a critical component of personal injury litigation.