What is the test for a defendant's right to be present at a trial?

Fairly read, these cases illustrate the basic principle that a criminal defendant's right to be present at certain stages of trial is a due process right that inures to the defendant's benefit. For that reason, the issue often involves determining whether the defendant's absence from a proceeding constitutes a denial or violation of due process. (See People v. Beardslee (1991) 53 Cal.3d 68, 103, 279 Cal.Rptr. 276, 806 P.2d 1311.) Logically, this determination is made after the fact, that is, after a proceeding is held without the defendant. The relevant considerations include whether the defendant suffered any damage or prejudice from being absent and whether the matters discussed at the proceeding bore a substantial relationship to the ability to defend against the charge. (Ibid. ) In other words, a defendant has a due process right to be present " to the extent that a fair and just hearing would be thwarted by his absence, and to that extent only. " (People v. Isby, supra, 30 Cal.2d at p. 894, 186 P.2d 405, italics added.)