Can a volunteer grand jury act impartially?

We do not, however, rest our decision on this ground. Cf. Beck v. Washington, supra, 369 U.S. at 546, 82 S.Ct. 955 (assuming arguendo that a state which resorts to the grand jury process must furnish an impartial grand jury). The grand jury not only may check a prosecutor's decision to proceed against a defendant, but may undertake investigations and make formal accusations on its own initiative. To the extent that a grand jury once utilized not only vetoes prosecutions, but initiates them, a constitutional requirement that the jury be capable of impartiality would not be inconsistent with the principle enunciated above, that the state was not under a constitutional mandate to utilize a grand jury system in the first instance. The petitioners have nonetheless failed to demonstrate that the Second August 1964 Grand Jury was unable to act fairly and impartially. Petitioners speculate that persons who volunteer for grand jury service commonly possess authoritarian personality traits which predispose them to pay undue heed to the prosecutor and to initiate proceedings against persons who may strike them as suspicious or "criminal-type" individuals. But simple willingness to render public service may sufficiently explain a citizen's propensity to volunteer, and petitioners have presented no concrete evidence to support their darker conjecture.