In People v. Eddie Thompson, the Court of Appeals of New York held that it was not ineffective assistance of counsel to keep a juror [William Peters] who was long-time friends with the prosecutor. In Thompson, the defendant, who was acquitted of second degree murder but convicted of manslaughter in the death of his girlfriend, argued that it was ineffective assistance of counsel for his attorney to fail to exercise a peremptory challenge to remove Peters. Although defense counsel did ask that the judge challenge Peters for cause, he never used one of his peremptories to strike him.
According to the court,
[i]t could be argued that counsel's decision not to use a peremptory challenge on Peters was a mistake for two reasons: because Peters, as a juror, would be biased in the prosecution's favor; and because, by not using a peremptory challenge to excuse him, counsel failed to preserve for appeal any claim that the court erred in rejecting the for-cause challenge.
The court made quick work of the first argument stating that
[it] is a weak one, because defense counsel may reasonably have thought Peters an acceptable juror from the defense point of view.
In contrast, the second argument merited more discussion. According to the court,
[c]ounsel's choice not to exercise a peremptory challenge deprived defendant of the opportunity to make that argument on appeal; under CPL 270.20 (2), where a defendant has not exhausted his peremptory challenges, a denial of a challenge for cause "does not constitute reversible error unless the defendant . . . peremptorily challenges such prospective juror."
In affirming the defendant's conviction, the court ultimately concluded that
counsel's mistake, if it was one, was not the sort of "egregious and prejudicial" error that amounts to a deprivation of the constitutional right to counsel