What are the specific requirements for demonstrating 'effective assistance of counsel' in a criminal case, and what constitutes a breach of this requirement?

To demonstrate 'effective assistance of counsel' in a criminal case, a defendant must meet a two-pronged test established in Strickland v. Washington. First, the defendant must show that their counsel's performance was deficient. This means that the attorney's representation fell below an objective standard of reasonableness, considering prevailing professional norms. This is a highly deferential standard, meaning courts presume that counsel's conduct falls within the wide range of reasonable professional assistance. The defendant must identify specific acts or omissions of counsel that were outside the range of professionally competent assistance. Second, the defendant must show that the deficient performance prejudiced the defense. This means that there is a reasonable probability that, but for counsel's unprofessional errors, the result of the proceeding would have been different. A 'reasonable probability' is a probability sufficient to undermine confidence in the outcome. It is not enough to show that the errors had some conceivable effect on the outcome of the proceeding. A breach of the requirement for 'effective assistance of counsel' occurs when both prongs of the Strickland test are met. Examples of deficient performance include failing to investigate crucial witnesses, failing to present available defenses, failing to adequately cross-examine key prosecution witnesses, providing incorrect legal advice that leads the defendant to make a detrimental decision (like rejecting a plea bargain), or sleeping through portions of the trial. To demonstrate prejudice, the defendant must show that these deficiencies likely altered the outcome. For instance, if counsel failed to call an alibi witness who could have provided credible testimony placing the defendant elsewhere during the crime, and there is no other strong evidence against the defendant, a court might find that the deficient performance prejudiced the defense. Similarly, if counsel failed to advise the defendant about a favorable plea bargain, and the defendant was subsequently convicted at trial and received a much harsher sentence, a court might find prejudice. It is important to note that strategic decisions made by counsel, even if ultimately unsuccessful, are generally not considered deficient performance if they were based on reasonable professional judgment after an adequate investigation.