defendant’s presumption of innocence and the state’s burden of establishing the defendant’s guilt beyond and to the exclusion of every reasonable doubt. When again asked if she could find the defendant not guilty if the state failed in its burden, this prospective juror candidly responded: “I don’t know.” When a similar question was later put to her, she responded: “No, not if it cannot be proved.” Later, after the denial of the challenge for cause, this juror ultimately stated that she could “be fair.”
The initial determination of a juror’s competence for cause lies within the discretion of a trial court, Singer v. State, 109 So.2d 7, 22 (Fla.1959); Ashley v. State, 370 So.2d 1191 (Fla. 3d DCA 1979). This discretion, however, is not unlimited.
At stake is the party’s right guaranteed by the Sixth Amendment to an impartial jury; the principal way this right is implemented is through the system of challenges exercised during the voir dire of prospective jurors.... Although a trial court has broad discretion in its conduct of voir dire, ... its exercise of that discretion is “subject to the essential demands of fairness.” [citations omitted]
United States v. Nell, 526 F.2d 1223, 1229 (5th Cir. 1976).
The test for determining the competence of a juror is not whether he will be able to control any bias or prejudice but rather whether he may lay aside those considerations and render his verdict solely upon the evidence presented and the instructions on the law given to him by the court. Singer v. State, supra; McCullers v. State, 143 So.2d 909 (Fla. 1st DCA 1962), cert, dismissed, 155 So.2d 696 (Fla.1963); § 913.03(10), Fla.Stat. (1979). Where there is any reasonable doubt as to a juror’s possessing the requisite state of mind so as to render an impartial verdict, the juror should be excused, Singer v. State, supra, and the defendant given the benefit of the doubt, Blackwell v. State, 101 Fla. 997, 132 So. 468 (1931); Walsingham v. State, 61 Fla. 67, 56 So. 195 (1911).
In this case it is true that the prospective juror ultimately gave affirmative answers lending credence to her ability to render a dispassionate, neutral, and unbiased verdict. On the other hand, that may have been the result of the psychological impact requiring such a declaration. See Irvin v. Dowd, 366 U.S. 717, 81 S.Ct. 1639, 6 L.Ed.2d 751 (1961). However, we do not need to speculate as to the inner workings of the juror’s mind, nor her sincerity. In Singer v. State, our Supreme Court stated:
[A] juror’s statement that he can and will return a verdict according to the evidence submitted and the law announced at the trial is not determinative of his competence, if it appears from other statements made by him or from other evidence that he is not possessed of a state of mind which will enable him to do so.
109 So.2d at 24. Gauged by the foregoing test, it is apparent that the challenge for cause to the juror should have been granted.
At the time the defendant challenged the prospective juror for cause, he had three remaining peremptory challenges. Following the denial of his challenge for cause of this prospective juror, he did not utilize any of his remaining peremptory challenges against her. Instead, he exercised his peremptory challenges against other prospective jurors to the point that all peremptory challenges were exhausted. For this reason, the state contends the defendant did not preserve the matter for appellate review arguing that he was first required to have exercised his peremptory challenge against the particular juror and then exhaust any remaining peremptory challenges and, following that, again renew his challenge for cause to the juror who was allegedly biased. We can find no support for such a proposition. Instead, we find the general rule to be that it is error for a court to force a party to exhaust his peremptory challenges on persons who should be excused for cause since it has the effect of abridging the right to exercise peremptory challenges. Swain v. Alabama, 380 U.S. 202, 85 S.Ct. 824, 13 L.Ed.2d 759 (1965); Stroud v. United States, 251 U.S. 15, 40 S.Ct. 50, 64 L.Ed. 103 (1919).