(1) Did the trial court err in instructing the jury on the elements of first degree murder by poison (see People v. Steger (1976) 16 Cal.3d 539, 544?546; People v. Mattison (1971) 4 Cal.3d 177, 183?184, 186)? (2) Was any such instructional error prejudicial?

Held:

The District Attorney charged Brown with first degree murder and prosecuted the charge on the theory that Brown had poisoned her newborn daughter by feeding her breast milk after smoking heroin and methamphetamine. The trial court instructed the jurors that to convict Brown of first degree murder they had to find she committed “an act” with the mental state of malice aforethought that was a substantial factor in causing her baby’s death and that she “murdered by using poison.” The instructions did not require the jury to find that Brown acted with any particular, heightened mental state when she fed her baby her breast milk. They thus allowed the jury to convict Brown of first degree murder if it found that she acted with malice — a mental state that normally would only support a conviction of second degree murder — and that poison was a substantial factor in causing her baby’s death. Based on these instructions, the jury convicted Brown of the first degree murder of her newborn daughter, for which the court imposed a sentence of 25 years to life in prison.

Brown argues that the jury instructions were incomplete because they did not require the jury to find she fed her daughter her breast milk with a mental state equivalent in turpitude to the willfulness, deliberation, and premeditation that generally distinguishes first degree murder from second degree murder. The Attorney General argues that the instructions were complete, because, in his view, proof that a defendant used poison is sufficient to elevate a murder to the first degree, without any proof of mental state beyond the showing of malice required for all murder convictions. We conclude Brown has the better argument.

[¶]

… [S]ince in a typical first degree murder by poison case there is no question that the defendant acted with willfulness, deliberation, and premeditation, we have never addressed whether there is a mental state component of first degree poison murder. We now clarify that to prove first degree murder by means of poison, the prosecution must show the defendant deliberately gave the victim poison with the intent to kill the victim or inflict injury likely to cause death.

The trial court’s instructions did not include this element of first degree poison murder. This was error. And because a rational jury could have concluded the prosecution did not prove beyond a reasonable doubt that Brown deliberately gave her newborn daughter the poisonous substances in her breast milk with the intent to kill her or inflict injury likely to cause her death, the error was prejudicial. Accordingly, we reverse Brown’s first degree murder conviction.

This case was decided on 3/2/2023.