When Is Hearsay Admissible in Expert Witness Testimony? California’s Sanchez Rule Explained

By David Gammill · Last reviewed: September 20, 2026

In California, an expert witness may rely on hearsay in forming an opinion and may tell the jury in general terms that they did so. The expert may not repeat case-specific hearsay to the jury as true unless it is proven by other evidence or falls within a hearsay exception. That is the rule of People v. Sanchez (2016) 63 Cal.4th 665, and California courts apply it in civil cases, including car crash and wrongful death trials. This page explains the rule in plain terms first, then covers the case law through 2026 for lawyers preparing an expert for trial.

• The rule: an expert may rely on hearsay and describe the kind of material they relied on in general terms; the expert may not repeat case-specific hearsay to the jury as fact unless it is proven another way or fits an exception.
• Background versus case-specific: what an expert knows about their field in general is fine to share; facts about the people and events in this particular case are not, unless proven.
• It applies in civil cases: California courts apply the Sanchez evidence rule in injury, wrongful death, family law and conservatorship cases. Only the confrontation clause part of Sanchez is limited to criminal trials.
• The fix is usually foundation: medical records with a custodian declaration, a witness with personal knowledge, or a hypothetical question built on facts already in evidence.
• Object correctly or lose the point: a Sanchez objection must name the ground and be followed by a motion to strike. A foundation objection alone does not preserve it.

If you were hurt in a crash and the insurance company is fighting over what your doctors and experts are allowed to say, call Gammill Law Accident & Injury Lawyers at 310-750-4149 for a free consultation, or send us a message through our contact page.

Two ways to read this page. Part 1 answers the question in plain terms for anyone who wants to understand what an expert can and cannot say in a California courtroom. Part 2 is written for lawyers preparing an expert for a California trial and covers the Supreme Court cases through 2026, the civil decisions, medical records, treating physicians, collision reports, dependent experts, objection practice and the federal comparison.

Part 1: The Plain Answer

What Is Hearsay, and Why Does It Matter for Experts?

Hearsay is a statement made outside the courtroom that is offered in court to prove that what it says is true. The California definition is in Evidence Code section 1200, which also states the basic rule: hearsay is inadmissible unless a law says otherwise. The reason is simple. The person who made the statement is not on the witness stand, so nobody can cross-examine them about it.

Experts create a special problem. An expert almost never has personal knowledge of what happened in the case. A doctor who never treated you reads your medical records. A crash reconstruction engineer reads witness statements and looks at photographs taken by someone else. An economist works from pay stubs and tax returns. Every one of those documents is hearsay when it is used to prove what it says. For decades, California let experts describe that material to the jury freely on the theory that the jury was not hearing it “for its truth,” only to understand the expert’s reasoning. In 2016 the California Supreme Court said that theory does not hold up.

What Is an Expert Allowed to Rely On?

An expert may rely on material that would not itself be admissible, as long as it is the kind of material experts in that field reasonably rely on. That rule has not changed. It is written into Evidence Code section 801, quoted here in full:

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.

Source: Cal. Evid. Code § 801, California Legislative Information (verified September 20, 2026).

In plain English, the statute asks two things. First, is the subject something a jury needs help with? Second, is the expert’s opinion built on the kind of information experts in that field actually use? The phrase “whether or not admissible” is the key. A treating surgeon can rely on an MRI report written by a radiologist. An economist can rely on payroll records. The law does not require every page the expert read to be admitted into evidence before the expert can form an opinion. What Sanchez controls is a different question: what the expert may say to the jury about those pages.

What Changed in People v. Sanchez?

Sanchez drew a line between two kinds of information: general background knowledge, which an expert may share freely, and case-specific facts, which an expert may not relate as true unless they are proven some other way. Background knowledge is what an expert learned about their field over a career: how a disc herniation shows up on imaging, how fast a car decelerates on dry pavement, how lost earnings are calculated. Case-specific facts are, in the Court’s words, facts “relating to the particular events and participants alleged to have been involved in the case being tried” (Sanchez, 63 Cal.4th at p. 676). What this plaintiff told her doctor, what a witness told the officer, what the plaintiff earned last year: those are case-specific.

The Court rejected the old “not for its truth” theory directly. When an expert tells the jury “the records show the patient reported neck pain the day after the crash” and then builds an opinion on it, the jury has to accept that report as true to accept the opinion. The Court put it this way: “When any expert relates to the jury case-specific out-of-court statements, and treats the content of those statements as true and accurate to support the expert’s opinion, the statements are hearsay” (Sanchez, 63 Cal.4th at p. 686). Like any other hearsay, those statements must come in through an exception or be proven independently. The old rule from People v. Gardeley (1996) 14 Cal.4th 605, which had let experts recite reliable hearsay to the jury, was disapproved.

Sanchez was a criminal case about a gang expert who read police reports to the jury. It has two parts. The first part interprets Evidence Code sections 801 and 802 and applies to every trial in California, civil or criminal. The second part applies the Sixth Amendment confrontation clause, which protects a criminal defendant’s right to face the witnesses against them, and that part applies only in criminal cases. When this page says “the Sanchez rule,” it means the first part.

Can the Expert Tell the Jury What They Relied On?

Yes, in general terms. Evidence Code section 802 lets a witness explain the reasons for an opinion and the matter it rests on:

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.

Source: Cal. Evid. Code § 802, California Legislative Information (verified September 20, 2026).

Sanchez read this section to mean that an expert “may still rely on hearsay in forming an opinion, and may tell the jury in general terms that he did so” (63 Cal.4th at p. 685). The Court explained the distinction: an expert may describe “the type or source of the matter relied upon,” but may not present “as fact, case-specific hearsay that does not otherwise fall under a statutory exception” (63 Cal.4th at p. 686). So an orthopedic expert may say, “I reviewed the emergency room records, the imaging studies and the operative report, and I examined the patient.” The expert may not say, “The emergency room note says she told the nurse her neck hurt immediately,” unless that note is in evidence or the patient has testified to it. The jury hears the category of material and can weigh the opinion accordingly; it does not hear the contents as proven fact.

What Happens If the Facts Are Proven Another Way?

Then the expert may use them freely. Sanchez itself names the routes: the fact can be “independently proven by competent evidence,” it can come in under a hearsay exception, or the evidence “can be admitted through an appropriate witness and the expert may assume its truth in a properly worded hypothetical question in the traditional manner” (63 Cal.4th at pp. 684, 686). In an injury case those routes look like this:

• A witness with personal knowledge testifies. The injured person describes the crash and the pain that followed. The treating physician testifies to what they saw and did. Once those facts are in evidence, a retained expert can build on them.
• The records come in under an exception. Medical records are usually admitted as business records under Evidence Code section 1271, most often through a custodian of records declaration. Once admitted, the records are evidence, and the expert may discuss their contents.
• The lawyer asks a hypothetical question. “Assume a 42-year-old woman with no prior neck complaints is struck from behind at 35 miles per hour and reports pain within an hour. What would you expect?” The assumed facts have to be proven by other evidence, but the expert can answer.

The Supreme Court has said several times since 2016 that Sanchez did not shrink what experts may consider, only what they may recite. In People v. Camacho (2022) 14 Cal.5th 77, 128, the Court wrote that “the limitations that Sanchez placed on expert testimony concern case-specific information that an expert relates to a jury, not materials upon which the expert relies,” and it repeated that sentence in People v. Curiel (2023) 15 Cal.5th 433, 458.

Does This Apply in Civil Cases Like Car Crashes and Wrongful Death?

Yes. The Court of Appeal first said so in People ex rel. Reisig v. Acuna (2017) 9 Cal.App.5th 1, 10, holding that the part of Sanchez that interprets Evidence Code sections 801 and 802 “applies in civil cases.” The same year, Conservatorship of K.W. (2017) 13 Cal.App.5th 1274 applied the rule in a civil conservatorship trial and found error where a psychologist recited the contents of hospital records that were never admitted into evidence. In re Marriage of Lietz (2024) 99 Cal.App.5th 664, 673 applied it in a divorce case to stop an appraiser from testifying to a lot size she had read in a public record nobody produced.

The case closest to an ordinary injury claim is Yaffee v. Skeen (2024) 106 Cal.App.5th 1281. A driver was hit from behind by a truck and hurt his spine. At trial his economist calculated lost earnings from payroll and personnel records, and his experts discussed his medical records. The defense objected under Sanchez. The Court of Appeal confirmed that Sanchez applies in civil actions, that an expert may still “consider and rely on case-specific hearsay in forming his or her opinions,” and that the economist’s testimony was not speculative because he explained the records he used, the variables in his calculation and how he checked the data. The trial judge’s comment to defense counsel during that trial is the practical lesson for both sides: if the expert relied on the records and you object that their contents are hearsay, “the answer is to move all those records in. You can’t have it both ways.”

For an injured person, this is why your lawyer spends so much time gathering complete medical records with custodian declarations, why your treating doctors matter as witnesses, and why you may be asked to testify in detail about your own symptoms. Each of those steps puts case-specific facts into evidence so that the experts can use them without objection.

Part 2: For Trial Lawyers

The Rule in One Sentence, and the Two Questions Every Sanchez Objection Asks

An expert may rely on anything of a type reasonably relied on in the field (Evidence Code section 801, subdivision (b)), may describe the kind and source of that material in general terms (section 802), and may not relate case-specific out-of-court statements as true unless they are independently proven or fall within a hearsay exception (Sanchez, 63 Cal.4th at p. 686). Every Sanchez objection turns on two questions, in order:

1. Is the information case-specific? The test is the nature of the information, not how the expert learned it. People v. Veamatahau (2020) 9 Cal.5th 16 held that a criminalist’s testimony about a pharmaceutical database identifying pills by imprint was background knowledge even though he looked it up for this case: “the location of a piece of information cannot change its nature.” By contrast, People v. Valencia (2021) 11 Cal.5th 818 held that the facts of particular past crimes are case-specific and must be proven by independently admissible evidence, not by an expert reading police reports.
2. Is the expert relating it as true? If the expert only describes the category of material (“I reviewed the treatment records from three providers”), section 802 permits it. If the expert conveys the contents and the opinion depends on those contents being accurate, it is hearsay and needs a route in. People v. Lamb (2024) 16 Cal.5th 400 illustrates the other side of the line: a firearms examiner who mentioned a prior examiner’s report only to explain that he had started his own examination from scratch was not relating it for its truth, so the Court found no clear Sanchez problem and resolved the claim on harmless error.

A practice point from Camacho: the prosecution there kept its expert inside Sanchez by asking leading yes-or-no questions on direct (“Did you review the file? Did it reflect a criminal history?”) after the trial court ruled the expert could not discuss the details. The same technique works on the plaintiff’s side with a life care planner or vocational expert whose underlying records are not yet in evidence.

The California Supreme Court Line, 2016 to 2026

Case	Year	What it added
People v. Sanchez, 63 Cal.4th 665	2016	The rule. Case-specific hearsay related as true is hearsay; background knowledge is not; experts may still rely on hearsay and describe it in general terms; independent proof, exceptions and hypotheticals are the routes in. Disapproved Gardeley.
People v. Veamatahau, 9 Cal.5th 16	2020	The background versus case-specific line turns on the nature of the information, not on whether the expert consulted a database or reference for this case. Disapproved People v. Stamps.
People v. Perez, 9 Cal.5th 1	2020	Forfeiture. A Sanchez objection was not forfeited at trials held before June 2016 because it would have been futile under Gardeley; for trials after Sanchez, ordinary Evidence Code section 353 forfeiture applies. Disapproved People v. Blessett.
People v. Valencia, 11 Cal.5th 818	2021	Facts of particular events and participants, there the predicate offenses in a gang case, are case-specific and require independently admissible proof. State-law Sanchez error is reviewed under Watson; testimonial confrontation error under Chapman.
People v. Camacho, 14 Cal.5th 77	2022	“The limitations that Sanchez placed on expert testimony concern case-specific information that an expert relates to a jury, not materials upon which the expert relies.” Leading yes-or-no questions kept the expert inside the rule.
People v. Curiel, 15 Cal.5th 433	2023	Restates Camacho: reliance is unrestricted; relating is what Sanchez governs.
People v. Lamb, 16 Cal.5th 400	2024	An expert’s reference to another examiner’s report to show the independence of his own work is a non-hearsay use; the Court found no clear Sanchez violation and held any error harmless.
People v. Barrera, S103358	June 1, 2026	The most recent restatement. Quotes the Sanchez rule at page 686 with “accord, Smith v. Arizona (2024) 602 U.S. 779, 802-803.” A pathologist conveyed a non-testifying radiologist’s findings, but the radiologist’s report was already in evidence, so the points were “independently proven.” The Court did not decide the state-law claim and found any error harmless beyond a reasonable doubt, noting that whether technical reports are testimonial “remains an evolving area of the law.”

How Civil Courts Apply Sanchez

Every published civil decision to reach the question has applied the state-law half of Sanchez and declined to extend the confrontation half. Reisig (gang injunction, 2017) said the sections 801 and 802 analysis “applies in civil cases such as this nuisance lawsuit” and that the Sixth Amendment rule “has not been extended to civil proceedings,” while leaving open a due process confrontation component in civil litigation. K.W. (2017) found error where the expert related behavioral history from hospital records that were never authenticated under section 1271, then held the error harmless under the Watson reasonable-probability standard because the expert also had personal contact with the conservatee and the conservatee testified about the same incidents. Conservatorship of S.A. (2018) 25 Cal.App.5th 438 is the mirror image: the records came in under section 1271 on custodian affidavits, so the expert “related only case-specific facts that were proved by admissible evidence” and there was no error.

Lietz (2024) shows how narrow the exclusion can be. The appraiser’s own lot-size figure was in her report; when counsel tried to have her testify that a public record showed a larger lot, the trial court excluded it because the record itself was never produced, and the Court of Appeal affirmed. Even the question “did you review the public record” on that point “would have violated Sanchez.” Yaffee (2024) then applied all of this in a rear-end truck crash, and added two points that matter most in injury practice: an economist’s lost-earnings opinion built on records not in evidence is not “conclusory” where the expert lists the types of documents, the variables and the verification steps; and a party that lets the testimony in without moving to strike has forfeited the Sanchez argument. Yaffee also relied on Zuniga v. Alexandria Care Center, LLC (2021) 67 Cal.App.5th 871, which held it was prejudicial error to exclude an expert entirely because the spreadsheets he relied on were inadmissible; section 801, subdivision (b) says “whether or not admissible,” and the question of what the expert may recite is separate from whether the expert may testify at all.

Medical Records and the Section 1271 Foundation

Medical records are the single largest source of Sanchez problems in injury trials, and the fix is almost always a business records foundation laid before the expert takes the stand. Section 1271 admits a record of an act, condition or event when it was made in the regular course of business, at or near the time, a custodian or other qualified witness testifies to its identity and mode of preparation, and the sources and method of preparation indicate trustworthiness. For records obtained by subpoena, Evidence Code section 1561 lets a custodian’s affidavit stand in for live testimony if it states the affiant’s authority, that the copy is a true copy, that the records were prepared in the ordinary course of business at or near the time of the event, the identity of the records, and the mode of preparation. Section 1562 then makes the copy admissible if the section 1271 requirements are met and presumes the affidavit’s statements true.

Two cases mark the boundary. In People v. McVey (2018) 24 Cal.App.5th 405, the proponent had medical records but no section 1561 declaration and no custodian; the records were inadmissible, and under Sanchez the expert “could not testify about the medical records” or relate their contents. The court added that compliance with a subpoena does not by itself make records admissible, and that police reports generally do not qualify as business records because they are created for use in litigation. In Wicks v. Antelope Valley Healthcare Dist. (2020) 49 Cal.App.5th 866, the opposite: the hospital records came with a custodian declaration, were properly authenticated as business records under section 1271, and were therefore a proper basis for the medical expert’s declaration. Wicks restates the older rule from Garibay v. Hemmat (2008) 161 Cal.App.4th 735 that an expert’s medical opinion has no evidentiary value when the records it rests on are not authenticated and in evidence.

The working rule for a plaintiff’s trial team: obtain every treating provider’s records by subpoena with a compliant section 1561 declaration, mark them, and move them into evidence before or during the first expert’s testimony. The Yaffee colloquy is the reason. Once the records are in, the Sanchez objection to the expert’s discussion of their contents falls away. If the defense objects to both the expert’s reliance and the admission of the records, that is the “both ways” position the Yaffee trial court refused to allow.

Treating Physicians

A treating physician has personal knowledge of what they observed, diagnosed and did, so that testimony is not hearsay at all. The California Supreme Court held in Schreiber v. Estate of Kiser (1999) 22 Cal.4th 31 that a treating physician is a “percipient expert” who may give both fact and opinion testimony, including opinions on causation, based on facts acquired independently of the litigation and informed by training and experience, without an expert witness declaration. Easterby v. Clark (2009) 171 Cal.App.4th 772 applied that rule to a treating surgeon’s opinion that the accident caused the need for surgery; the difference between a treater and a retained expert “is not the content of the testimony, but the context” in which the physician learned the facts.

Sanchez still applies to the parts of a treater’s testimony that are not personal knowledge. What the patient said during treatment is usually admissible as a statement for purposes of medical diagnosis or treatment, or comes in through the patient’s own testimony. What a prior provider wrote in records the treater reviewed is case-specific hearsay unless those records are in evidence. And an opinion the treater formed only from records handed over by counsel for litigation is the territory of a retained expert, with its own disclosure rules. The safest sequence in an injury trial is to call the treaters first, so that the retained experts who follow can build on facts already in the record.

Traffic Collision Reports and Reconstruction Experts

The traffic collision report is not evidence in California, and Sanchez means a reconstruction expert cannot smuggle it in by reciting it. Vehicle Code section 20013 provides that no required accident report “shall be used as evidence in any trial, civil or criminal, arising out of an accident.” Box v. California Date Growers Assn. (1976) 57 Cal.App.3d 266, a motorcycle crash case, called it “well established that traffic accident reports are not admissible in evidence” and affirmed the exclusion of the report and its diagram, while upholding the reconstruction expert’s opinion on the motorcycle’s path after impact because a proper foundation was laid. Carlton v. Department of Motor Vehicles (1988) 203 Cal.App.3d 1428 added that an officer’s report does not qualify as a business or official record and that the officer’s conclusion about who was “most responsible” is a legal conclusion, not a proper subject of expert opinion, even if the officer testified live.

Put together with Sanchez, the rules for a reconstructionist are clear. The expert may rely on the report in forming an opinion and may say so in general terms. The expert may use scene measurements, photographs, vehicle damage, event data recorder downloads, roadway geometry and physics, and may testify to the opinions those support. The expert may not relate the officer’s narrative, the witness statements recorded in the report, or the officer’s fault determination as true. Where the underlying facts are needed, they come in through the officer’s live testimony about what the officer personally observed and measured, through the drivers and witnesses themselves, or through a hypothetical question built on that testimony.

Life Care Planners, Economists and Other Dependent Experts

A dependent expert is one whose opinion assumes another expert’s conclusions, and Sanchez requires that the chain be proven link by link. A life care planner assumes the treating physician’s recommendations for future care. An economist assumes the life care plan and the vocational expert’s opinion about work capacity. Each of those upstream opinions is an out-of-court statement to the downstream expert. Section 801, subdivision (b) lets the downstream expert rely on them. Sanchez bars the downstream expert from telling the jury what the upstream expert concluded unless the upstream expert has testified or the opinion is otherwise in evidence.

Two statutes shape the practice. Evidence Code section 804 lets the adverse party call and cross-examine any person whose opinion or statement the expert relied on, and states that nothing in the section makes admissible an expert opinion that is inadmissible because it rests on another person’s statement. Evidence Code section 803 requires the court, on objection, to exclude an opinion “based in whole or in significant part on matter that is not a proper basis,” but lets the witness restate the opinion if a proper basis remains after the improper matter is set aside. The order of witnesses does most of the work: physician, then planner, then economist, each assuming only what the jury has already heard. Yaffee is the precedent that an economist who describes the records, the variables and the verification steps has given a reasoned opinion, not a conclusory one.

Billing Experts at the Sanchez and Howell Intersection

Medical bills are hearsay when offered to prove the charges were incurred, so they need the same section 1271 foundation as the treatment records, and a billing expert on either side may rely on them but may not recite them as true until they are in. In Yaffee, the bills came in under the business records exception and supported the expert testimony that followed. The measure of recoverable medical expenses is a separate question governed by Howell v. Hamilton Meats & Provisions, Inc. (2011) 52 Cal.4th 541, which held that a plaintiff whose expenses are paid through private insurance recovers no more than the amounts paid or still owing. Yaffee‘s own medical-expense awards were reversed on that Howell issue; the damages rule is the subject of another page, and this one stops at the evidence question.

Preserving the Objection and the “Both Ways” Trap

A Sanchez objection must be specific, timely and followed by a motion to strike, or it is forfeited. Evidence Code section 353 bars reversal for the erroneous admission of evidence unless the record shows a timely objection or motion to strike “so stated as to make clear the specific ground,” and unless the error caused a miscarriage of justice. People v. Espinoza (2018) 23 Cal.App.5th 317, 320 held that an objection on “lack of foundation” alone forfeited the Sanchez hearsay point. Yaffee held that defendants who objected during the testimony but never moved to strike it forfeited the argument that the expert had conveyed the truth of the personnel records. Perez confirmed that after June 2016 the ordinary section 353 rule governs; the futility excuse applied only to trials held before Sanchez was decided.

For the objecting party, the sequence is: object at the first case-specific recital, naming Sanchez and hearsay (not foundation alone); renew as needed; move to strike the testimony at the close of the examination; and ask for a section 803 ruling on whether a proper basis remains for the opinion. A section 352 objection is a different objection, aimed at cumulative or inflammatory detail, and does not preserve the Sanchez point (Perez, 9 Cal.5th at pp. 13-14 discusses the distinction). Prejudice on appeal is measured under Watson: whether a more favorable result was reasonably probable without the error (K.W.; Valencia).

For the proponent, the trap runs the other way. A party that objects to the expert’s recital of the records and also objects to admitting the records is asking the court to keep the facts out entirely; the Yaffee trial court refused, and the appellate court noted that the defense then elected to keep the bills out rather than press the point. Decide before trial which records you want in evidence, get the section 1561 declarations, and move them in. Everything your experts need to say about those records becomes admissible the moment the records are.

How Federal Court Differs

Federal court reaches a similar practical result by a different route, and the vocabulary is different enough to trip a California lawyer who tries a diversity case downtown. The rules below are federal law, not California law; this section is included for comparison only.

Question	California (Evidence Code and Sanchez)	Federal (Rules of Evidence and Smith v. Arizona)
May the expert rely on inadmissible material?	Yes. Section 801(b): “whether or not admissible,” if of a type reasonably relied on in the field.	Yes. Rule 703: facts or data “need not be admissible” if experts in the field would reasonably rely on them.
May the expert tell the jury the contents of case-specific hearsay?	No, unless independently proven or within an exception (Sanchez at 686). The expert may describe the type and source in general terms (section 802).	Only if the proponent shows the probative value in helping the jury evaluate the opinion “substantially outweighs” the prejudicial effect (Rule 703, a reverse-403 balance), and in criminal cases subject to the Confrontation Clause.
Must the basis be disclosed before the opinion?	Section 802 permits stating the reasons and matter on direct; the court may require a preliminary examination of the basis.	Rule 705: the expert may state the opinion first without testifying to the underlying facts; the basis may be required on cross.
What did the highest court say about the “not for its truth” theory?	Rejected for case-specific facts. “It cannot logically be maintained that the statements are not being admitted for their truth” (Sanchez at 686).	Rejected in criminal cases in Smith v. Arizona (2024) 602 U.S. 779: when an expert conveys an absent analyst’s statements in support of the opinion and they support it only if true, they come in for their truth. The 2012 plurality in Williams v. Illinois, 567 U.S. 50, which had accepted the theory, never commanded a majority.
Does the confrontation clause apply?	Criminal cases only (Sanchez; Reisig; K.W.).	Criminal cases only. Smith left open when a lab report is “testimonial” and remanded that question.
What may the expert still do?	Rely on the material; describe it generally; testify to background knowledge; answer hypotheticals on proven facts; discuss records once admitted.	Testify to lab practices and general standards from personal knowledge; explain general techniques; answer hypotheticals (“if or assuming some out-of-court statement were true”), with the assumed fact proven separately (Smith).

The California Supreme Court reads the two systems as aligned on the core point: in Barrera (June 1, 2026) it quoted the Sanchez rule and added “accord, Smith v. Arizona.” The remaining federal difference is Rule 703’s balancing test, which gives a federal judge discretion to let the jury hear otherwise inadmissible basis facts that a California judge applying Sanchez would exclude.

Is This Law Current?

Yes. The statutes quoted and cited on this page reflect California law as of the review date at the top, verified against the official California Legislative Information site and independent mirrors. Evidence Code sections 801 and 802 have been unchanged since the Evidence Code took effect in 1967. The most recent California Supreme Court restatement of the Sanchez rule is People v. Barrera (June 1, 2026), which repeats the rule and notes its agreement with Smith v. Arizona. The Court has not narrowed Sanchez in any decision through the review date; the movement in the case law has been in applying it to civil trials and in defining what counts as case-specific.

A One-Page Sanchez Checklist for Trial Lawyers

We keep a one-page checklist for preparing an expert under Sanchez: what to sort as case-specific before disclosure, the foundation to have on file for each record set, the order of dependent witnesses, and the exact objection and motion-to-strike sequence. California attorneys can request it at our Sanchez expert checklist page. It is a working document, not legal advice, and it does not create an attorney-client relationship.

Legal References

1. Cal. Evid. Code § 801. Bases of expert opinion; “whether or not admissible.”
2. Cal. Evid. Code § 802. Statement of reasons and matter relied upon on direct examination.
3. Cal. Evid. Code § 803. Exclusion of an opinion based on improper matter; restating the opinion on a proper basis.
4. Cal. Evid. Code § 804. Examination of the person whose opinion or statement the expert relied on.
5. Cal. Evid. Code § 1200. The hearsay rule.
6. Cal. Evid. Code § 1271. Business records exception.
7. Cal. Evid. Code § 1561 and § 1562. Custodian of records affidavit for subpoenaed records; admissibility of the copy.
8. Cal. Evid. Code § 353. Timely, specific objection or motion to strike required to preserve error.
9. Cal. Evid. Code § 352. Discretionary exclusion of evidence.
10. Cal. Evid. Code § 721. Cross-examination of an expert on the matter relied upon and the reasons for the opinion.
11. Cal. Veh. Code § 20013. Accident reports not to be used as evidence in any trial.
12. Fed. R. Evid. 703 and Fed. R. Evid. 705. Federal comparison only.
13. People v. Sanchez (2016) 63 Cal.4th 665.
14. People v. Veamatahau (2020) 9 Cal.5th 16.
15. People v. Perez (2020) 9 Cal.5th 1.
16. People v. Valencia (2021) 11 Cal.5th 818.
17. People v. Camacho (2022) 14 Cal.5th 77.
18. People v. Curiel (2023) 15 Cal.5th 433.
19. People v. Lamb (2024) 16 Cal.5th 400.
20. People v. Barrera (June 1, 2026, S103358) ___ Cal.5th ___.
21. People ex rel. Reisig v. Acuna (2017) 9 Cal.App.5th 1.
22. Conservatorship of K.W. (2017) 13 Cal.App.5th 1274.
23. Conservatorship of S.A. (2018) 25 Cal.App.5th 438.
24. People v. McVey (2018) 24 Cal.App.5th 405.
25. People v. Espinoza (2018) 23 Cal.App.5th 317.
26. Wicks v. Antelope Valley Healthcare Dist. (2020) 49 Cal.App.5th 866; Garibay v. Hemmat (2008) 161 Cal.App.4th 735.
27. Zuniga v. Alexandria Care Center, LLC (2021) 67 Cal.App.5th 871.
28. In re Marriage of Lietz (2024) 99 Cal.App.5th 664.
29. Yaffee v. Skeen (2024) 106 Cal.App.5th 1281.
30. Schreiber v. Estate of Kiser (1999) 22 Cal.4th 31; Easterby v. Clark (2009) 171 Cal.App.4th 772.
31. Box v. California Date Growers Assn. (1976) 57 Cal.App.3d 266; Carlton v. Department of Motor Vehicles (1988) 203 Cal.App.3d 1428.
32. Howell v. Hamilton Meats & Provisions, Inc. (2011) 52 Cal.4th 541.
33. People v. Gardeley (1996) 14 Cal.4th 605 (disapproved in Sanchez).
34. Williams v. Illinois (2012) 567 U.S. 50; Smith v. Arizona (2024) 602 U.S. 779.

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About the Author, and How to Reach Gammill Law

David Gammill is a former Los Angeles County Deputy District Attorney who has tried over 100 cases to verdict, first as a prosecutor and then as a trial lawyer for injured people. Every case is different, and past results do not guarantee a similar outcome. Gammill Law represents people in personal injury, wrongful death and civil rights cases across California, and accepts trial referrals and co-counsel arrangements for trial from other attorneys.

The firm has recovered more than $100 million for California clients across verdicts and settlements. Its results include a $21.1 million wrongful death verdict, a $16 million school sexual abuse verdict and a $12 million whistleblower retaliation verdict; each came from a specific case with its own facts, and no result is a promise about any other case. The full list is on the firm’s case results page.

If you or someone in your family was hurt because someone else was careless, request a free case evaluation or call 310-750-4149. There are no upfront legal fees; a fee is collected only if we win, under a written contingency fee agreement that complies with California law.

Disclaimer: This article is educational and informational in nature. It does not constitute legal advice for any specific situation, and reading it does not create an attorney-client relationship. Every case turns on its own facts, and no result is guaranteed; consult a licensed California attorney about your own circumstances.