Preservation of evidence
Michigan's judges have adopted a rule that excludes from trial any evidence that was not preserved for the adversary to examine. Unfortunately, that rule is not applied uniformly.
Under the "spoliation of evidence" rule, a party having custody of evidence cannot make it available to the party's own expert for analysis, and then allow it to be destroyed before the adversary's expert can evaluate it. To preclude this kind of behavior--even if it is innocent or merely negligent--the Courts have held that the evidence and any expert opinion based upon it will not be admitted into a trial if it was never available to the adversary.
This rule follows a general pattern in Michigan and in other states, of excluding evidence that is not properly preserved by a party having custody or control. In some cases, the party having custody may suffer the additional disadvantage of an instruction to jurors that they may or should "infer" that the lost evidence was damaging to the case of the party having custody but failing to produce the evidence. The Sixth Circuit Appeals Court recently voiced implicit criticism of Michigan for failing to recognize a simliar rule in the context of "third-party" spoliation in Adkins v. Wolever. Adkins was allegedly assaulted in his jail cell by Wolever, however, Wolever's [State] employer "lost" the videotape of the encounter. Under Michigan rules, no sanction was applicable under Michigan law.