Does section 1123 of the Penal Code allow for a mistrial where a juror's illness or other good cause causes the juror to be unable to perform his duty and there are no alternate jurors?

Penal Code section 1123 authorizes a mistrial where a juror is unable to perform his duty because of illness or "other good cause" and where no alternate is available. The words "other good cause" must have been meant to cover situations such as the inability of a healthy juror to serve due to some emergency. Under these circumstances, if there were no alternate juror, a 12-person jury would be unavailable and legal necessity for a mistrial would exist. (See Curry v. Superior Court, supra, 2 Cal.3d at pp. 713-714, 87 Cal.Rptr. 361, 470 P.2d 345.)

A juror's misconduct has a different effect. Absent a valid objection to the juror's continuing to serve, a full jury remains. The fact that a juror's actions or beliefs would provide "good cause" for his replacement if an alternate were available does not mean that there is "legal necessity" for a mistrial where no alternate is available. (See People v. Davis (1972) 27 Cal.App.3d 115, 120, 103 Cal.Rptr. 494.)