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

"A trial court is obliged to instruct ... on the general principles of law which relate to the issues presented by the evidence. [Citations.] When the evidence is minimal and insubstantial, there is no duty to instruct. [Citations.]" (People v. Cooksey (2002) 95 Cal.App.4th 1407, 1410.) "[T]he existence of `any evidence, no matter how weak' will not justify instructions on a lesser included offense, but such instructions are required whenever evidence that the defendant is guilty only of the lesser offense is `substantial enough to merit consideration' by the jury. [Citations.] `Substantial evidence' in this context is ` "evidence from which a jury composed of reasonable [persons] could...conclude[]"' that the lesser offense, but not the greater, was committed." (People v. Breverman (1998) 19 Cal.4th 142, 162.)