People v. Vasquez, 30 Cal. App. 5th 786

Defendant Tyshaun Vasquez and codefendant Jordan E. assaulted victim Eddie Ray Smith Jr. at a park; Vasquez stomped the victim about 20 times and punched him after he was on the ground. Smith died; autopsy found a C2–C3 neck fracture likely caused by blunt-force trauma.
Smith had prior cervical surgery with metal rods adjacent to the fracture, which may have acted as a fulcrum and made the neck more susceptible to breaking. Most other injuries were nonlethal.
Vasquez was charged with special-circumstance first degree murder and attempted second degree robbery; the jury acquitted him of first degree murder and attempted robbery but convicted him of second degree murder.
Defense requested an instruction on involuntary manslaughter (unlawful killing without malice) as a lesser-included offense; the trial court denied the request and told the jury only murder instructions (and granted second-degree murder instruction).
On appeal, the court considered whether substantial evidence supported the involuntary manslaughter instruction and whether denial was prejudicial; it reversed and remanded for retrial, concluding an instruction should have been given and the error was prejudicial.

Issue	People’s Argument	Vasquez’s Argument	Held
Whether the trial court was required to instruct on involuntary manslaughter as a lesser-included offense of murder	No; evidence showed conduct (stomping ~20 times) was so brutal that defendant was subjectively aware his conduct endangered life	Yes; substantial evidence (nonlethal external injuries, preexisting neck rods causing anomalous fatal fracture) supported reasonable juror finding of no malice	Court: Instruction required — substantial evidence supported manslaughter instruction
Whether denying the instruction was prejudicial	Harmless: overwhelming evidence of malice made a manslaughter instruction immaterial	Prejudicial: defense centered on malice; jury acquitted on related counts, deliberations were lengthy and conflicted, so reasonable probability of more favorable result	Court: Error prejudicial under state law; reversal and remand for retrial

People v. Breverman, 19 Cal.4th 142 (lesser-included instruction required when supported by substantial evidence)
People v. Knoller, 41 Cal.4th 139 (implied malice requires subjective awareness that conduct endangers life)
People v. Millbrook, 222 Cal.App.4th 1122 (view evidence favorably to defendant when assessing need for lesser-included instruction)
People v. Guillen, 227 Cal.App.4th 934 (group jail attack supported awareness of life-endangering risk)
People v. Evers, 10 Cal.App.4th 588 (severe injuries and prior abuse supported awareness of risk)
People v. Moye, 47 Cal.4th 537 (harmless-error analysis where jury rejected lesser theories)
People v. Flood, 18 Cal.4th 470 (harmlessness where defendant effectively conceded element)
People v. Gonzalez, 5 Cal.5th 186 (discussion of malice and murder definitions)