What is the legal test for admitting expert testimony at trial?

Several principles came into play in the trial court's rulings at issue here. First, only relevant evidence is admissible at trial. (Evid. Code, 350.) Relevant evidence is that which has "any tendency in reason to prove or disprove any disputed fact that is of consequence to the determination of the action." (Id., 210.) The trial court has the duty to determine the relevance and thus the admissibility of evidence before it can be admitted. (Id., 400, 402.) Evidence Code section 352 gives the trial court the discretion to exclude relevant evidence if the probative value of the evidence is substantially outweighed by the probability its admission will create a substantial danger of undue prejudice, confusing the issues or misleading the jury. (People v. Rodrigues (1994) 8 Cal.4th 1060, 1124.) "'In general, the trial court is vested with wide discretion in determining

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relevance and in weighing the prejudicial effect of proffered evidence against its probative value.'" (People v. Valencia (2008) 43 Cal.4th 268, 286.) We review the trial court's determinations as to relevancy and prejudice for abuse of discretion. (People v. Hamilton (2009) 45 Cal.4th 863, 945.)

Second, under Evidence Code section 801, a matter may be the subject of expert testimony "if it is 'sufficiently beyond common experience that the opinion of an expert would assist the trier of fact.' That is not to say, however, that the jury need be wholly ignorant of the subject matter of the expert opinion in order for it to be admissible. [Citation.] Rather, expert opinion testimony '"will be excluded only when it would add nothing at all to the jury's common fund of information, i.e., when 'the subject of inquiry is one of such common knowledge that men of ordinary education could reach a conclusion as intelligently as the witness'" [citation].' [Citation.]" (People v. Jones (2012) 54 Cal.4th 1, 60.) "'The trial court has broad discretion in deciding whether to admit or exclude expert testimony [citation], and its decision as to whether expert testimony meets the standard for admissibility is subject to review for abuse of discretion.' [Citation.]" (People v. Jones (2013) 57 Cal.4th 899, 946.)

Finally, a defendant has the right to have the trier of fact consider pertinent evidence on his behalf. "Evidence Code section 352 must bow to the due process right of a defendant to a fair trial and to his right to present all relevant evidence of significant probative value to his defense." (People v. Reeder (1978) 82 Cal.App.3d 543, 553; accord, People v. Cunningham (2001) 25 Cal.4th 926, 998-999.) However, this does not mean "a defendant has a constitutional right to present all relevant evidence in his favor, no matter how limited in probative value

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