What is the case law on discretionary exclusion of relevant evidence in a defence case?

None of the considerations supporting the discretionary exclusion of relevant evidence substantially outweighed the probative value of the evidence at issue here. Presentation of evidence at the heart of the defense would not have represented an "undue" consumption of time. There was no risk of prejudice associated with the evidence. "The prejudice referred to in Evidence Code section 352 applies to evidence which uniquely tends to evoke an emotional bias against ... [one party] ... and which has very little effect on the issues." (People v. Wright (1985) 39 Cal.3d 576, 585, 217 Cal.Rptr. 212, 703 P.2d 1106 [internal quotation marks omitted].) Evidence bearing on appellant's state of mind was highly probative, and had no "unique tendency" to evoke any emotional bias against the prosecution. Evidence that appellant might have had reason to fear for his life would not have "confused the issue." It would have further illuminated the situation the jury was required to evaluate.

Appellant was prejudiced by the erroneous exclusion of this evidence. It is unnecessary to determine whether the error in this case was of constitutional dimension because the error was prejudicial even under the standard of People v. Watson (1956) 46 Cal.2d 818, 836, 299 P.2d 243 [different result must have been "reasonably probable" in the absence of the error].