tion to attempt to exercise it contrary to validly promulgated regulations. Thus, Nixon actually stands for a very different proposition than the one for which the Court cites it: faced with a specific claim of abuse of prosecutorial discretion, Nixon makes clear that courts are not powerless to intervene. And none of the other prosecutorial discretion cases upon which the Court rests involved a claim that discretion had been abused in some specific way.
Moreover, for at least two reasons it is inappropriate to rely on notions of prosecutorial discretion to hold agency inaction unreviewable. First, since the dictum in Nixon, the Court has made clear that prosecutorial discretion is not as unfettered or unreviewable as the half-sentence in Nixon suggests. As one of the leading commentators in this area has noted, "the case law since 1974 is strongly on the side of reviewability." 2 K. Davis, Administrative Law § 9:6, p. 240 (1979). In Blackledge v. Perry, 417 U. S. 21, 28 (1974), instead of invoking notions of "absolute" prosecutorial discretion, we held that certain potentially vindictive exercises of prosecutorial discretion were both reviewable and impermissible. The "retaliatory use" of prosecutorial power is no longer tolerated. Thigpen v. Roberts, 468 U. S. 27, 30 (1984). Nor do prosecutors have the discretion to induce guilty pleas through promises that are not kept. Blackledge v. Allison, 431 U. S. 63 (1977); Santobello v. New York, 404 U. S. 257, 262 (1971). And in rejecting on the merits a claim of improper prosecutorial conduct in Bordenkircher v. Hayes, 434 U. S. 357 (1978), we clearly laid to rest any notion that prosecutorial discretion is unreviewable no matter what the basis is upon which it is exercised:
"There is no doubt that the breadth of discretion that our country's legal system vests in prosecuting attorneys carries with it the potential for both individual and institutional abuse. And broad though that discretion may
