A preliminary hearing—also known as a probable cause hearing—is held before trial to determine whether the evidence is strong enough to show that the defendant committed the crime and must stand trial for it. In other words, the purpose of the preliminary hearing is for the court to determine whether there is probable cause demonstrating the defendant committed the crime.
The preliminary hearing or “prelim” is the defendant’s chance to hear and challenge the prosecution’s evidence and is usually a preview of what the prosecution’s presentation of the case will look like at trial. If the judge believes there is probable cause demonstrating the defendant committed a crime, the case may proceed to trial. But if the judge does not believe there is probable cause to support some or all of the criminal charges, some or all of the charges may be reduced or dismissed.
There is no jury in a preliminary hearing, and it is not a trial, but it does some of the same procedures as a trial and may look like an abbreviated or mini-trial. For example, the prosecution will call witnesses and introduce evidence, and the defense can cross-examine those witnesses. But the defense cannot object to the court hearing certain pieces of evidence that may not be admissible at trial.
Laws and rules regarding preliminary hearings—including the types of cases in which they are required or available and the time periods in which they must be held—vary from state to state and in the federal court system. A preliminary hearing is generally required in all cases in which the defendant is charged with a felony offense—unless the defendant waives the preliminary hearing, which is rare.