The facts and procedural history of the case, Bank of Nova Scotia v. United States, is discussed, with particular emphasis on a Federal district court's use of its supervisory power to dismiss an indictment because of violations of the Federal Rules of Criminal Procedure. The Supreme Court held that the district court's supervisory powers could not be invoked to dismiss an indictment when the error did not 'substantially influence' the grand jury's decision. Because the error has not had substantial influence on the grand jury, it is harmless. A court cannot invoke its supervisory power to dismiss an indictment based on harmless nonconstitutional error. The article examines the consequences of subordinating the supervisory power doctrine to the harmless error rule, arguing that in this case the Court unnecessarily burdens defendants and broadens the scope of the harmless error doctrine beyond its legislative intent. 194 footnotes.