What is the current state of the law on the duty of a court to inquire into the propriety of multiple representations?

The Sixth Amendment imposes no affirmative duty on a trial court "to inquire into the propriety of multiple representations." Cuyler v. Sullivan, 446 U.S. 335, 348, 100 S.Ct. 1708, 1718, 64 L.Ed.2d 333 (1980). To establish a Sixth Amendment violation, "a defendant who raised no objection at trial must demonstrate that an actual conflict of interest adversely affected his lawyer's performance." Id. However, what is meant by "adversely affected" is glossed by the direction that a defendant "need not demonstrate prejudice in order to obtain relief." Id. at 349-350, 100 S.Ct. at 1719. His burden is less than showing actual harm; he must show actual conflict.