What is the legal test for admissible expert testimony in a sexual assault case?

In addressing challenges to the sufficiency of evidence, "the reviewing court must examine the whole record in the light most favorable to the judgment to determine whether it discloses substantial evidence evidence that is reasonable, credible and of solid value such that a reasonable trier of fact could find the defendant guilty beyond a reasonable doubt. [Citation.] The appellate court presumes in support of the judgment the existence of every fact the trier could reasonably deduce from the evidence. [Citations.] The same standard applies when the conviction rests primarily on circumstantial evidence. [Citation.] Although it is the jury's duty to acquit a defendant if it finds the circumstantial evidence susceptible of two reasonable interpretations, one of which suggests guilt and the other innocence, it is the jury, not the appellate court that must be convinced of the defendant's guilt beyond a reasonable doubt. [Citation.] `"If the circumstances reasonably justify the trier of fact's findings, the opinion of the reviewing court that the circumstances might also reasonably be reconciled with a contrary finding does not warrant a reversal of the judgment. [Citation.]"' [Citation.]" (People v. Kraft (2000) 23 Cal.4th 978, 1053-1054.)

"California law permits a person with `special knowledge, skill, experience, training, or education' in a particular field to qualify as an expert witness [citation] and to give testimony in the form of an opinion [citation]. Under Evidence Code section 801, expert opinion testimony is admissible only if the subject matter of the testimony is `sufficiently beyond common experience that the opinion of an expert would assist the trier of fact.' [Citation.] The subject matter of the culture and habits of criminal street gangs, of particular relevance here, meets this criterion. [Citations.]" (People v. Gardeley (1996) 14 Cal.4th 605, 617.)