However, the court may specifically direct the defendant to be personally present at any particular proceeding or portion thereof. 23 law or other matters as to which his presence bears no reasonable, substantial relation to his opportunity to defend the charges against him. (Harris, supra, 43 Cal.4th at p. 1306, fn. omitted.) In Kentucky v. Stincer (1987) 482 U.S. 730 [96 L.Ed.2d 631], the United