Proposition 115, approved by the voters in 1990, abrogated traditional principles of criminal discovery in favor of a statutory scheme. (Pen. Code, 1054, subd. (e); In re Littlefield (1993) 5 Cal. 4th 122, 129 [19 Cal. Rptr. 2d 248, 851 P.2d 42].) Now, discovery is permitted in criminal cases only where authorized by statute "or as mandated by the Constitution of the United States." ( Pen. Code, 1054, subd. (e); see Izazaga v. Superior Court (1991) 54 Cal. 3d 356, 378 [285 Cal. Rptr. 231, 815 P.2d 304].) No statute provides for discovery of material relevant to a claim of selective or discriminatory prosecution. However, in United States v. Armstrong (1996), the United States Supreme Court held that the federal Constitution requires that a criminal defendant be permitted to discover such material, as long as he or she first produces " 'some evidence tending to show the existence of the essential elements of the defense.' " (Id. at p. 468 [116 S. Ct. at p. 1488].) "The claimant must demonstrate that the . . . prosecutorial policy [1] 'had a discriminatory effect and [2] that it was motivated by a discriminatory purpose." (Armstrong, supra, 517 U.S. at p. 465 [116 S. Ct. at p. 1187], italics added.) Armstrong made it clear that a defendant seeking discovery to support a claim of selective prosecution has a high burden. The court explained that "[t]he justifications for a rigorous standard for the elements of a selective-prosecution claim . . . require a correspondingly rigorous standard for discovery in aid of such a claim." (Id. at p. 468 [116 S. Ct. at p. 1488].) It further stated that "the showing necessary to obtain discovery should . . . be a significant barrier to the litigation of insubstantial claims." ( Id. at p. 464 [116 S. Ct. at p. 1486].)