State v. Cuyler
In State v. Cuyler, 110 Wis. 2d 133, 142, 327 N.W.2d 662 (1983), Cuyler was charged with second-degree sexual assault and two counts of enticing a child for immoral purposes with the trial being a credibility battle between the accuser and the accused. See Cuyler, 110 Wis. 2d at 134.
Cuyler attempted to offer as witnesses two police officers who would have testified to his character for truthfulness, but the trial court ruled that such testimony was not admissible. See Cuyler, 110 Wis. 2d at 136.
The Court reversed in the interests of justice, holding that because credibility was a determinative issue, the exclusion of such evidence adversely affected Cuyler's defense and he should have been allowed to offer evidence as to his truthfulness. See Cuyler, 110 Wis. 2d at 141.
The court further noted that "the jury cannot search for truth if it cannot consider relevant and admissible evidence on a crucial issue in the case." Cuyler, 110 Wis. 2d at 142.