In Dennis v. United States (1966) 384 U.S. 855, the court concluded defense counsel should be permitted to review grand jury testimony for potential impeachment evidence at trial under circumstances where the court had the authority to order disclosure and the state conceded the need to preserve the secrecy of the grand jury testimony was now minimal. (Id. at pp. 869-874.) The Dennis court explained that it was not realistic "to assume that the trial court's judgment as to the utility of material for impeachment ... purposes, however conscientiously made, would exhaust the possibilities. In our adversary system, it is enough for judges to judge. The determination of what may be useful to the defense can properly and effectively be made only by an advocate." (Id. at pp. 874-875.)