When will a judge conduct a hearing to determine if there is a potential conflict of interest?

This court consistently has required a trial judge, when a potential conflict of interest arises, to conduct a hearing to determine whether a conflict exists such as would prevent the accused from receiving advice and assistance sufficient to afford him the quality of representation guaranteed by the Sixth Amendment. We have said that the defendant should be fully apprised by the trial court of the facts underlying the potential conflict, and the defendant should be given the opportunity to express his views. Moreover, it is the rule that an appellant claiming a conflict by counsel must demonstrate some specific instance of prejudice resulting from the joint representation that would warrant vacatur of his conviction. United States v. Carrigan, 543 F.2d 1053 (1976).