 Glasser established that unconstitutional multiple representation is never harmless error . Once the Court concluded that Glasser 's lawyer had an actual conflict of interest , it refused " to indulge in nice calculations as to the amount of prejudice " attributable to the conflict . The conflict itself demonstrated a denial of the " right to have the effective assistance of counsel . " Thus , a defendant who shows that a conflict of interest actually affected the adequacy of his representation need not demonstrate prejudice in order to obtain relief . But until a defendant shows that his counsel actively represented conflicting interests , he has not established the constitutional predicate for his claim of ineffective assistance . 
