A motion to suppress evidence is a request by a defendant to have particular evidence excluded from trial. The defense often files this motion far in advance of the trial; if the defendant prevails, the prosecution or judge may be forced to dismiss the case. The importance of the evidence to the prosecution’s case determines whether dismissal is warranted.
Motions to suppress evidence are most prevalent in Fourth Amendment instances involving search and seizure. Defendants may also submit them in other instances, such as when eyewitness identification is required. A defendant may claim that the identification technique was so unfair that the court should prevent the prosecution from presenting its findings during the trial.
For instance, Wallace and Poot are strolling down the street. They’re not acting suspiciously, and the cops have no cause to believe they’ve lately committed a crime. Nonetheless, Officers Carver and Haulk arrive in a vehicle beside them. They instruct Wallace and Poot to come to a halt, then leap out of the vehicle and frisk both of them. Wallace’s jacket pocket contains a “eight-ball” of cocaine, according to Officer Carver. Wallace is charged with narcotics possession by the prosecution. Wallace’s attorney moves to suppress the cocaine evidence. The court approves the request because the police lacked reasonable suspicion for detaining Wallace and Poot and had no grounds to search them. Because the prosecution cannot establish the offense without proof, it seeks to drop charges, which the court approves. (For further information, see What is the difference between an arrest and a detention or “stop and frisk”?)