Not a finding that someone automatically lied or lost the case, an adverse inference is a permitted conclusion that a judge or jury may draw when missing evidence would likely have been unfavorable to the party who failed to preserve, produce, or explain it. It usually comes up after spoliation of evidence - for example, deleted video, discarded parts, altered records, or missing phone data. The inference can be mild or strong depending on the facts. In some cases, the court gives a jury instruction; in others, the judge applies the inference when weighing proof.

Practically, this matters because missing evidence can shift how the remaining evidence is viewed. If a business loses inspection logs, a driver deletes texts, or a property owner fails to keep surveillance footage after notice of a claim, the court may allow an adverse inference instead of requiring direct proof of what the missing item showed. That can strengthen a plaintiff's negligence case or weaken a defendant's defense.

In Delaware, adverse inference issues are commonly handled under the court's inherent authority and Superior Court Civil Rule 37 when evidence preservation failures affect discovery. Delaware courts have discussed spoliation sanctions, including adverse inferences, in cases such as Beard Research, Inc. v. Kates (Del. Ch. 2009). In an injury claim, sending a prompt preservation notice can matter because once evidence is lost, the fight often becomes about what the court will allow the jury to assume.