What is the test for ineffective assistance in a criminal case?

As we explained recently in People v. Mitchell (2008) 164 Cal.App.4th 442 at page 467: "`[T]he mere failure to object rarely rises to a level implicating one's constitutional right to effective legal counsel.' [Citation.] If, as here, the record fails to show why counsel failed to object, the claim of ineffective assistance must be rejected on appeal unless counsel was asked for an explanation and failed to provide one or there can be no satisfactory explanation. [Citation.] `A reviewing court will not second-guess trial counsel's reasonable tactical decisions.' [Citation.]"

Defendant's ineffective assistance argument does not even begin to explain how counsel's failure to object fell below the standard of a reasonably competent attorney or how it resulted in prejudice. Even if defendant's prosecutorial misconduct claim was meritorious, defendant makes no attempt to explain how counsel could not possibly have made a tactical decision not to emphasize the matter to the jury by objection. Merely saying that deficiency and prejudice are both "fairly shown" does not make it so. "We will not address a claim that defendant has failed to develop." (People v. Mitchell, supra, 164 Cal.App.4th at p. 467.)