Nolo's Plain-English Law Dictionary

Overt Act

In criminal law, an action that might be innocent by itself, but when part of the preparation and active furtherance of a crime, is evidence of a defendant's participation in the crime. For example, when the first World Trade Center defendants were put on trial, evidence of their renting a van, buying explosives, obtaining a map of downtown New York City, and going back and forth to the World Trade Center was admitted to establish overt acts that proved their complicity in the bombing.