State v. Foy
In State v. Foy, 206 Wis. 2d 629, 557 N.W.2d 494 (Ct. App. 1996), the Court explained:
To succeed on a claim of ineffective assistance of counsel, a defendant must show that his attorney's performance was deficient and that the deficient performance prejudiced his defense. There is a strong presumption that the attorney has rendered effective assistance and made all significant decisions exercising reasonable professional judgment.
In addition, a defendant must show that there is a reasonable probability that, but for trial counsel's unprofessional errors, the result of the proceeding would have been different. Claims of ineffective assistance of counsel present mixed questions of law and fact. The trial court's findings of fact will not be disturbed unless clearly erroneous. However, the determinations of whether counsel's performance was deficient and whether the defendant was prejudiced are questions of law, which we review de novo.
Deficient performance means that counsel "made errors so serious that counsel was not functioning as the 'counsel' guaranteed ... by the Sixth Amendment to the United States Constitution." In determining whether there was deficient performance, we make every effort to avoid relying on hindsight. We focus on counsel's perspective at the time of trial, and the burden is on the defendant to overcome a strong presumption that counsel acted reasonably within professional norms. An attorney's performance is not deficient unless it is shown that, "in light of all the circumstances, the identified acts or omissions were outside the wide range of professionally competent assistance." (557 N.W.2d at 497-498.)