Cuyler, Correctional Superintendent v. Sullivan

Summary

The Court, in an opinion delivered by Justice Powell, held that a state trial judge has no duty to inquire into the propriety of multiple representation absent an objection and that a mere possibility of a conflict of interest is insufficient to establish ineffective assistance of counsel; an actual conflict that adversely affected counsel’s performance is required. Justice Brennan filed a concurrence in part, agreeing with Part III of the opinion and the result but not joining Part IV. Justice Marshall filed a concurrence in part and dissent in part, joining Parts I‑III but dissenting from the majority's standard, arguing that the presence of an actual conflict should be sufficient to reverse the conviction and would have affirmed the Court of Appeals judgment.