United States v. Mechanik
Citation and Court
475 U.S. 66 (1986), Supreme Court of the United States
Facts
Two government witnesses testified simultaneously before a federal grand jury in violation of Federal Rule of Criminal Procedure 6(d), which requires that only one witness be present while grand jurors are deliberating or voting. The defendants moved to dismiss the indictment after discovering the violation. They were ultimately convicted at trial.
Issue
Whether a violation of Rule 6(d)‘s requirement that only one witness be present during grand jury deliberations requires dismissal of an indictment after the defendant has been convicted at trial.
Holding
A violation of Rule 6(d) is harmless beyond a reasonable doubt once a defendant has been convicted at trial by a jury, because the trial conviction demonstrates probable cause existed and cures any prejudice from the grand jury irregularity.
Rule / Doctrine
Grand jury procedural violations are subject to harmless error analysis after a trial conviction. A subsequent guilty verdict by a petit jury establishes that there was in fact probable cause to believe the defendant committed the charged offense, rendering speculative any claim that the grand jury defect prejudiced the defendant.
Significance
Mechanik limits defendants’ ability to challenge indictments based on grand jury procedural errors when they have already been convicted at trial. It reflects the Court’s reluctance to allow technical violations to invalidate convictions supported by sufficient trial evidence.