In what circumstances will a defendant be able to appeal against his conviction for the murder of an elderly woman who was found guilty of murder by reason that he failed to obtain a certificate of probable cause?

Likewise, the defendant in this case attacks the validity of his plea. The prosecution agreed to a maximum sentence of 25 years to life in return for defendant's plea. Yet, defendant now attacks that maximum sentence on the ground that it is cruel and unusual punishment. By arguing that the maximum sentence is unconstitutional, he is arguing that part of his plea bargain is illegal and is thus attacking the validity of the plea. Having failed to obtain a certificate of probable cause, defendant cannot appeal. (See also, People v. Sabados (1984) 160 Cal.App.3d 691, 695-696 [where defendant pleaded guilty to first degree murder with the knowledge that his sentence would be 25 years to life, his claim that the sentence was disproportionate could not be considered on appeal absent a certificate of probable cause because "his challenge is to the validity of his plea to first degree murder."].)