When a document relevant to an issue in a case is destroyed, the trier of fact sometimes may infer that the party who obliterated it did so out of a realization that the contents were unfavorable. Before such an inference may be drawn, there must be a sufficient foundational showing that the party who destroyed the document had notice both of the potential claim and of the document’s potential relevance. Even then, the adverse inference is permissive, not mandatory. If, for example, the factfinder believes that the documents were destroyed accidently or for an innocent reason, then the factfinder is free to reject the inference.
When evidence indicates that a party is aware of circumstances that are likely to give rise to future litigation and yet destroys potentially relevant records without a particularized inquiry, a factfinder may reasonably infer that the party probably did so because the records would harm its case.
Kelley v. United Airlines, 176 F.R.D. 422, 427-28 (D. Mass. 1997)