What is the test for substituting an alternate juror in a criminal trial?

Situations continued to arise where the interests of justice made it desirable to discharge a juror for reasons other than those expressly set forth in the statute. For example, People v. Burns (1948) 84 Cal.App.2d 18, presented a question of the propriety of substituting an alternate juror when a regular member of the panel was found, after the commencement of the trial, to be under indictment for a felony. Although this situation did not fit squarely within the language of the statute, the court believed justice would not be served by allowing this juror to remain on the panel.