From time to time I try to get a judge to accept and instruct on an adverse inference. Or at least argue it. Generally adverse inferences come up when evidence is “lost” or there has been a refusal of discovery. Basically the argument goes that if the evidence isn’t provided for a reason within the control of the adverse “party,” then it can be argued or presumed that the information would have been favorable to the accused. Here is a nice little piece – from a civil case – that is of interest.
District Court concludes duty to preserve electronic and other evidence commenced on pre-complaint telephone call, warranting adverse-inference instruction sanction, in KCH Services, Inc. v. Vanaire, Inc., et al., _ F.Supp.2d _ (W.D. Ky July 22, 2009) (Civil Action No. 05-777-C).
It seems to me that CID/NCIS/OSI/CGIS have a duty to preserve evidence, along with gathering it. To the extent you may be able to find problems with evidence gathering, handling, witness notes or statements, etc., there may be a way to fit the adverse inference into a botched investigation argument. Just a thought.
/tip Federal Evidence blog.