Suppress means to exclude or prevent disclosure, often used in reference to evidence sought to be introduced at a criminal trial. A motion to suppress is a request to a judge to keep out evidence at a trial or hearing, often made when a party believes the evidence was unlawfully obtained. The party making the motion often claims the evidence was obtained as the result of an unlawful search and seizure.
The court decides this issue after a hearing in which the defense attorney cross-examines the officers involved in the case, and presents legal argument about why the evidence should be suppressed. If this motion is successful, the case may be dismissed entirely.
