In the United States v. Cronic case of 1983, the Supreme Court ruled on whether a defendant's Sixth Amendment right to counsel was violated due to his attorney's lack of preparation time before trial. The defendant, Charles Raymond Cronic, had been convicted for mail fraud but argued that he did not receive effective assistance from his lawyer because they only had 25 days to prepare for a complex trial involving thousands of documents and over forty witnesses. However, the Supreme Court disagreed with this argument stating that short preparation time does not automatically constitute ineffective assistance unless there is proof showing that it resulted in actual prejudice against the accused during their defense at trial. Therefore, even though an attorney may have limited time to prepare for a case or may make mistakes during representation, these factors do not necessarily mean that they provided ineffective counsel as per Sixth Amendment rights.

In the dissenting opinion for United States v. Cronic, Justice White argued that the majority's decision was too broad and could potentially undermine the public's confidence in the justice system. He contended that there should be a presumption of effectiveness regarding counsel unless there is clear evidence to suggest otherwise. According to him, it would be more appropriate to assess whether or not an attorney’s performance had been deficient on a case-by-case basis rather than assuming incompetence due to circumstances such as limited preparation time. Furthermore, he disagreed with the majority's view that certain situations automatically deny defendants their Sixth Amendment right to effective assistance of counsel without requiring them to demonstrate actual prejudice resulting from their lawyer’s performance.