Essentially, when plaintiffs try to present evidence on a point essential to their case and can't because the document has been destroyed (by the defendant), the jury can infer that the evidence would have been adverse to (the defendant), and adopt the plaintiff’s reasonable interpretation of what the document would have said...."[1][better source needed] Adverse inference applies in United States civil trials, but not criminal trials; criminal defendants are protected by the Fifth Amendment, which guarantees a right against self-incrimination (including self-incrimination by way of silence).
[2] In civil trials, adverse inference may be imposed as a sanction by the court in reaction to spoliation, such as willful destruction of relevant emails.
The adverse inference is based upon the presumption that the party who controls the evidence would have produced it if it had been supportive to their case.
Adverse inference can also apply to a witness who is known to exist whom a party refuses to identify or produce.
Under English law, the court and the jury may draw an adverse inference from fact that someone did not mention a defence when given the chance to do so if charged with an offence.