In California, an objection to an “improper hypothetical” is raised when a question is posed that asks a witness to assume facts that are not in evidence or that are unreasonable or unsupported by the record. Hypothetical questions are often used to ask expert witnesses to apply their expertise to a set of assumed facts, but if the hypothetical question presents an inaccurate or misleading set of circumstances, it can confuse the witness or the jury. For example, a question that asks a witness to assume facts that haven’t been established in the case, or that misrepresents the evidence, can lead to an objection. This is especially problematic when the hypothetical question is posed as though the facts are already established when they have not been proven.
To avoid such objections, it is essential that the facts assumed in a hypothetical question are either already in evidence or are reasonable extrapolations of the evidence presented during the trial. California Evidence Code section 801 allows experts to testify based on hypothetical facts, but the hypothetical must be based on facts that are supported by the evidence, or the testimony may be deemed improper. If a question poses an improper hypothetical, the court may sustain the objection, directing the attorney to rephrase the question with facts that are properly in evidence or more accurately reflect the case. This ensures that the witness’s testimony is grounded in the actual facts of the case and not speculative or misleading assumptions.
