What is the test for a jury to determine whether a defendant who intentionally commits an intentional unlawful killing without malice is guilty of voluntary manslaughter?

Murder involves the unlawful killing of a human being with malice aforethought, but a defendant who intentionally commits an unlawful killing without malice is guilty only of voluntary manslaughter. (People v. Breverman (1998) 19 Cal.4th 142, 153.) For purposes of voluntary manslaughter, an intentional unlawful killing can lack malice when the defendant acted under a " 'sudden quarrel or heat of passion' " or when the defendant acted under "[an] unreasonable but good faith belief in having to act in self-defense." (Id. at p. 154.) Two years after the trial here, in People v. Lasko (2000) 23 Cal.4th 101, we clarified that voluntary manslaughter may also apply where a defendant "acting with conscious disregard for life and knowing that the conduct endangers the life of another, unintentionally but unlawfully kills in a sudden quarrel or heat of passion." (Id. at p. 104.) We further explained that "the presence or absence of an intent to kill is not dispositive of whether the crime committed is murder or the lesser offense of voluntary manslaughter" (id. at p. 110) and that it was error to instruct the jury otherwise. (Id. at p. 111.) Accordingly, the trial court erred here when it instructed the jury that voluntary manslaughter requires a finding that the "killing was done with the intent to kill."