What is the test for a jury to reach a unanimous verdict?

"Except as provided by law, the jury cannot be discharged after the cause is submitted to them until they have agreed upon their verdict and rendered it in open court, unless by consent of both parties, entered upon the minutes, or unless, at the expiration of such time as the court may deem proper, it satisfactorily appears that there is no reasonable probability that the jury can agree." ( 1140.) "The determination whether there is reasonable probability of agreement rests in the sound discretion of the trial court. [Citations.] The court must exercise its power, however, without coercion of the jury, so as to avoid displacing the jury's independent judgment 'in favor of considerations of compromise and expediency.' [Citation.]" (People v. Miller (1990) 50 Cal.3d 954, 994.)

There always is a potential for coercion once the trial judge has learned the majority of jurors favor conviction. (People v. Sheldon (1989) 48 Cal.3d 935, 959.) However, the inadvertent discovery of the nature of the division is not a basis for a mistrial; nor is simply asking the jury to continue deliberating inherently coercive. Whether a unanimous vote was coerced requires a close analysis of the court's conduct from the perspective of the holdout jurors. (See id. at pp. 959-960.) Nothing in this record may be construed as an attempt to pressure the jury to reach a verdict. "The trial court made no coercive remarks and exerted no undue pressure on the minority juror[s] to change [their] vote. [Citation.]" (Id. at p. 959.) Rather, the court made a discretionary determination that there was a reasonable probability the jury would reach a unanimous decision.