Cal. EVID § 803
This is the official text of Cal. EVID § 803, part of California’s Evidence Code — sets the rules for what evidence is admissible in California courts.
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Official statutory text
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.
Status: in_force · Read it on the official government site
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