When will a grand jury consider the defense of extreme emotional disturbance?

In People v. Valles (1984) 62 N.Y.2d 36, 476 N.Y.S.2d 50, 464 N.E.2d 418, the defendant was indicted for second degree murder. He claimed the district attorney erroneously failed to instruct the grand jury on the defense of extreme emotional disturbance when that defense had been "suggested" by the evidence. The court held that: "The extent of the District Attorney's obligation to instruct the Grand Jury concerning defenses must be defined with reference to the role of that body. 'The primary function of the Grand Jury in our system is to investigate crimes and determine[839 P.2d 1071] whether sufficient evidence exists to accuse a citizen of a crime and subject him or her to criminal prosecution' [citation]. Viewed from this perspective, the question of whether a particular defense need be charged depends upon its potential for eliminating a needless or unfounded prosecution. [p] The appropriate distinction for this purpose is between exculpatory and mitigating defenses. An exculpatory defense is one that would, if believed, result in a finding of no criminal liability.... [p] When a defense is urged in mitigation, on the other hand, it is not done in an effort to avoid criminal liability entirely; rather, it is an attempt to reduce the gravity of the offense committed.... Because consideration of such defenses by the Grand Jury would not prevent unfounded criminal accusation, but would, at best, merely reduce the degree of the crime charged, their presentation to the Grand Jury will not ordinarily be mandated. The District Attorney is free to seek an indictment for the highest crime the evidence will support. It is not necessary that, having presented a prima facie case and those complete defenses suggested by the evidence, the District Attorney go further and present defenses in mitigation, which ordinarily will involve matters for resolution by the petit jury upon a full record." (Id., 62 N.Y.2d 36, 476 N.Y.S.2d at p. 51, 464 N.E.2d 418.)