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.
Cal. Evid. Code § 803
Expert and Other Opinion Testimony Generally
Applied in 26 court decisions — leading case 8 Cal. 4th 587 - People v. Leahy (1994)
Most recently applied in 247 Cal. Rptr. 3d 875 - Esparza v. Safeway, Inc. (June 2019)
Enacted by Stats. 1965, Ch. 299.
How often courts cite this section
Court decisions citing this, by year. The dip in the last several years is a data-coverage gap, not a real trend — our corpus holds fewer opinions from the most recent years, so recent citations are undercounted.
Official source: California Legislative Information. Reproduced from public-domain California statutes; confirm against the official source for the current text. Not legal advice.