Postpartum Mental Disorder – Expert Testimony Admissible?

In 2011, in Sacramento County, Ka Yang placed her baby girl, Mirabelle, in a microwave oven and operated it for multiple minutes, killing the baby due to thermal injuries and burns.

Yang was 29 years old at the time.  She was born in the United States and is of Hmong descent (from Cambodia).  She lived in Sacramento with her husband, Chi Lo, and their three young sons then ages four, seven and eight.  She was thrilled to have a girl and took good care of all her kids.

Yang’s husband was a long-haul truck driver. Typically, he was on the road during the week and was home only on weekends, but at times he would be gone up to 14 days at a time.

Yang began having seizures at age 13 or 14 and by the time of the killing had experienced more than 100 seizures in her lifetime.  She took medication to control the seizures, but did not believe the medicine helped.  Her husband had witnessed many of her seizures.  She would fall the ground, her eyes would roll back in her head, she would moan, roll up on a ball, drool and often lost control of her bladder.  The seizures would last two to five minutes.

After the death of her daughter, she told first responders that she did not know how the baby was injured, but guessed that she injured the baby while unconscious and having a seizure.

A jury in Sacramento County found her guilty of first-degree murder and assault on a child resulting in death.  The judge sentenced her to 25-years-to-life, plus one year for use of a dangerous weapon in the murder, plus another 25-years-to-life, stayed under Penal Code § 654, for the assault on her daughter resulting in death.

Her defense at trial was that she killed her daughter while unconscious due to an epileptic seizure and thus she did not have the intent to kill.  The prosecution countered her claim by eliciting expert testimony regarding postpartum mental disorders and testimony relying upon Yang’s privileged psychological records, even though Yang’s psychologist specifically found Yang negative for postpartum depression.

Nonetheless, the prosecution relied upon an expert who relied upon Yang’s medical records to theorize that Yang was motivated to kill her daughter by hallucinations related to an undiagnosed postpartum psychosis.

Yang made a motion for a new trial, which was denied.  In the motion, Yang argued that the trial court judge, Steve W. White, abused his discretion by allowing expert testimony regarding postpartum mental disorders without a sufficient factual basis and by admitting defendant’s privileged psychological records that he had ruled were inadmissible earlier.  She argued such evidence was irrelevant and the errors in admitting such evidence and testimony were not harmless when considered together or in the cumulative.

Yang then appealed to the Third Appellate District Court in San Francisco. 

The Third Appellate District agreed with Yang, starting from the fundamental point that only relevant evidence is admissible at trial.  Evidence Code § 350.  Under Evidence Code § 352, evidence is inadmissible if when it is substantially more prejudicial than probative if it poses an intolerable risk to the fairness of the proceedings or the reliability of the outcome and renders the defendant’s trial fundamentally unfair.”  People v. Chavez (2018) 22 Cal. App. 5th 663, 702.

The motive theory was the relevance of the prosecution expert’s testimony, although the expert had actually screened Yang as negative for postpartum mental disorders after her daughter’s birth. 

Under the cumulative error doctrine, the reviewing court must “review each allegation and assess the cumulative effect of any errors to see if it is reasonably probable the jury would have reached a result more favorable to defendant in their absence.  When the cumulative effect of the errors deprives the defendant of a fair trial and due process, reversal is required.”  People v. Williamson (2009) 170 Cal. App. 4th 567, 646; People v. Cunningham (2001) 25 Cal. 4th 926, 1009 (series of trial errors, though independently harmless, “may in some circumstances rise by accretion to the level of reversible and prejudicial error”).

Additionally, multiple errors may create a “negative synergistic effect, rendering the degree of overall unfairness more than that flowing from the sum of individual errors.”  People v. Hill (1998) 17 Cal. 4th 800 at 847.

We present this summary to exemplify how a judge, apparently stumped by the evidence, permitted the prosecution to proceed on a theory that was fundamentally flawed from the outset because it did not rely upon admissible evidence at all.  This type of mistake can reoccur and no doubt may unless defense counsel is vigilant to assert his or her client’s rights.

The citation for the Third Appellate District Court ruling discussed above is People v. Ka Yang (3rd App. Dist., 2021) 67 Cal. App. 5th 1, 281 Cal. Rptr. 3d 794.

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