What is the effect of the use of alternate jurors in the penalty trial of a murder defendant?

The use of alternate jurors serves the state's interest in preserving administrative convenience. The alternates, empaneled with the original jurors, would hear the guilt phase evidence. Empaneling these alternates would not significantly delay the jury selection process because the number of those jurors who will actually sit on the guilt phase jury and are unable to serve on the penalty jury is likely to be small. Jurors who strongly oppose capital punishment may not be excluded from the penalty trial unless they make it "unmistakably clear" that they "would automatically vote against the imposition of capital punishment without regard to any evidence that might be developed at the trial." (Witherspoon v. Illinois (1968) 391 U.S. 510 at pp. 522-523, fn. 21, 88 S.Ct. at pp. 1776-1777, fn. 21, 20 L.Ed.2d 776.) Of this small group many who have such strong convictions may likely be excluded at the outset by voir dire. They may (1) express a desire to have themselves excluded from participating in a capital trial, (2) be excluded on a peremptory challenge by the prosecution, or (3) be excluded for cause if they cannot render an impartial verdict on the issue of guilt.