Is a defendant entitled to a jury instruction reflecting his or her theory of defense?

It is well-established that a criminal defendant is entitled to a jury instruction reflecting his or her theory of defense "for which there is some foundation in the proof, no matter how tenuous that defense may appear to the trial court." United States v. Dove, 916 F.2d 41, 47 (2d Cir.1990). The defense theory in the instant case was that instead of the single conspiracy to possess (buy) cocaine with the intent to distribute, there were separate conspiracies consisting of a "buyer" group and a "seller" group.