U.S. v. Mackin

In prosecution on unlawful possession of firearm charge, Dist. Ct. erred in denying defendant’s motion for mistrial based on claim that govt. violated its Rule 16 obligation to turn over complete copy of continuity slip used to track firearm’s chain of custody. Copy of incomplete continuity form that had been given to defendant prior to trial formed central part of defendant’s defense, and defendant was entitled to copy of complete and correct form once govt. had produced incomplete form during discovery. Moreover, defendant established prejudice since production of complete form: (1) would have given defendant notice that his chain of custody defense was without merit; and (2) would have given defendant ability to seek out viable guilty plea options. Ct. rejected govt. claim that it was not required to tender complete form in absence of knowledge that said form would play role in defendant’s defense.