The merger doctrine was set forth in People v. Ireland (1969) 70 Cal .2d 522. People v. Chun (2009) 45 Cal.4th 1172 reviewed the history of the Ireland merger doctrine and held: "When the underlying felony is assaultive in nature . . . we now conclude that the felony merges with the homicide and cannot be the basis of a felony-murder instruction. An 'assaultive' felony is one that involves a threat of immediate violent injury. In determining whether a crime merges, the court looks to its elements and not the facts of the case. Accordingly, if the elements of the crime have an assaultive aspect, the crime merges with the underlying homicide even if the elements also include conduct that is not assaultive. . . This approach both avoids the necessity of consulting facts that might be disputed and extends the protection of the merger doctrine to the potentially less culpable defendant whose conduct is not assaultive. This conclusion is also consistent with our repeatedly stated view that the felony-murder rule should not be extended beyond its required application. We do not have to decide at this point exactly what felonies are assaultive in nature, and hence may not form the basis of a felony-murder instruction, and which are inherently collateral to the resulting homicide and do not merge. But shooting at an occupied vehicle under section 246 is assaultive in nature and hence cannot serve as the underlying felony for purposes of the felony-murder rule." (People v. Chun, supra, at p. 1200.)