What is the legal test for instructing a jury to convict a defendant of a lesser offence?

If testimony is reasonably susceptible to a jury's finding of a lesser offense, a sua sponte duty to instruct on that offense arises. If not, the jury may properly be presented only with the elements of the greater offense. In such a case, the evidence would support only a finding of guilt or no guilt, as charged. (People v. Leal (2009) 180 Cal.App.4th 782, 792 (Leal) [no LIO instruction required "where the evidence shows that if the defendant is guilty, he is guilty of the greater offense"].)

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