People v. Julian, 246 Cal. Rptr. 3d 517

Defendant Cody Julian was convicted by a jury of four counts of lewd acts on a child (Pen. Code, § 288(a)) and one count of sexual penetration of a child under 10 (Pen. Code, § 288.7(b)); appeal followed.
Allegations arose from interactions between Julian and four minor sisters; the principal complainant (Child 2, then 10) testified to multiple instances of digital and penile penetration in settings including an RV; other sisters gave largely non‑corroborative or exculpatory testimony.
The People presented CSAAS (Child Sexual Abuse Accommodation Syndrome) expert testimony through clinical psychologist Anthony Urquiza; beyond describing CSAAS, Urquiza testified about statistical rates of false allegations (stating false reports occur roughly 1–8% of the time and at times characterizing them as very rare).
Defense counsel did not object to Urquiza’s statistical testimony and on cross‑examination elicited further study citations that the expert used to reiterate low false‑report rates; defense counsel also asked a detective whether he believed Child 2, and the detective answered yes.
The appellate court concluded Urquiza’s statistical probability testimony and the detective’s credibility opinion were inadmissible because they improperly bolstered the complainant’s credibility and usurped the jury’s role; the court also held defense counsel was ineffective for failing to object, and reversed and remanded for a new trial.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Admissibility of expert statistical testimony about false‑report rates	Urquiza’s statistics explain general rarity of false allegations and aid juror understanding of CSAAS	Statistics exceeded CSAAS scope and improperly opined on credibility/guilt	Reversed: statistical probability evidence inadmissible and prejudicial
Effect of expert statistics on fairness of trial	Statistical evidence corroborates complainant and discredits defense inconsistencies	Such statistics distract jury and supplant fact‑finding on credibility	Reversed: admission deprived defendant of a fair trial
Trial counsel’s failure to object to inadmissible evidence (ineffective assistance)	No strategic reason for silence; counsel’s cross opened more statistical testimony	People argue no objection = waiver	Held ineffective assistance under Strickland; prejudice shown given central credibility dispute
Whether defense questioning that elicited detective’s belief in complainant prejudiced defendant	Detective’s assent supports People’s case and was a permissible witness reaction	Such opinion testimony usurps jury’s role on credibility	Held improper and contributed to prejudice; supports reversal

People v. McAlpin, 53 Cal.3d 1289 (explaining permissible scope of CSAAS testimony)
People v. Bowker, 203 Cal.App.3d 385 (prohibiting expert predictive conclusions that jury apply syndrome to facts)
People v. Collins, 68 Cal.2d 319 (warning against expert statistical evidence that supplants jury fact‑finding)
Snowden v. Singletary, 135 F.3d 732 (11th Cir.) (vacating where expert testified children tell truth 99.5% and thereby impermissibly bolstered witnesses)
Powell v. State, 527 A.2d 276 (Del.) (rejecting expert percent‑testimony that improperly bolstered complainant credibility)