When a defendant is charged with conspiracy to commit a lesser included crime, what is the duty of the court to instruct the jury on all necessarily included offenses?

A trial court has a sua sponte duty to instruct on all necessarily included offenses supported by the evidence. (People v. Breverman (1998) 19 Cal.4th 142, 148-149.) This duty prevents either party from presenting the jury with an "'unwarranted all-or-nothing choice'" and encourages a verdict no harsher or more lenient than the evidence merits. (Id. at p. 155.) When conspiracy is charged, the jury must be instructed on lesser included offenses that could reasonably be true objects of the conspiracy. (People v. Fenenbock (1996) 46 Cal.App.4th 1688, 1706.) A lesser offense is included in a greater offense if either the statutory elements of the greater offense, or the facts actually alleged in the accusatory pleading, include all the elements of the lesser offense, such that the greater cannot be committed without also committing the lesser. (People v. Smith (2013) 57 Cal.4th 232, 244.) An instruction on a lesser included offense should only be given if there is substantial evidence that the defendant committed the lesser offense without also committing the greater. (Ibid.)