What is the test for a defendant to argue that he was excused from objecting to jury instructions?

^2. Respondent does not argue that defendant forfeited the right to make this argument. However, we seriously question whether defendant's claims regarding jury instructions were preserved for appellate review. It is settled that a defendant's failure to object to jury instructions forfeits the claim on appeal. (People v. Virgil (2011) 51 Cal.4th 1210, 1260.) In light of defendant's claim that he was excused from objecting because the instructions affected his substantial rights ( 1259), and to forestall any later charge brought in a habeas proceeding, we proceed to the merits.

^3. To be sure, involuntary manslaughter may be based on criminal negligence, long defined in California as follows: " '[T]here must be a higher degree of negligence than is required to establish negligent default on a mere civil issue. The negligence must be aggravated, culpable, gross, or reckless, that is, the conduct of the accused must be such a departure from what would be the conduct of an ordinarily prudent or careful man under the same circumstances as to be incompatible with a proper regard for human life, or, in other words, a disregard of human life or an indifference to consequences.' " (People v. Penny (1955) 44 Cal.2d 861, 879.) This definition is generally applicable where a defendant commits a lawful act without due caution, resulting in death, which was not an issue in this case. (People v. Butler, supra, 187 Cal.App.4th at p. 1007.)