Judge will analyze and consider the factors if the case should go to trial or be dismissed for lack of evidence.
Most DUI/DWI cases do not reach the preliminary hearing stage. Often the defendant pleads guilty at the arraignment. Even if the defendant pleads guilty, this stage is used only in case of a felony DUI/DWI in some states while others use a grand jury indictment method.
Preliminary hearing is a procedure designed to take place shortly after arrest, usually before the filing of a formal accusation. Its purpose is to have a judge decide whether there is enough evidence to justify holding the defendant for trial. If a preliminary hearing is held, the prosecution presents its evidence and the defendant has a right to make a statement himself and to call witnesses in his behalf. He is warned that anything he says may be used against him at a subsequent trial and that he is under no obligation to call witnesses or testify himself. At the conclusion of all the evidence, the judge decides whether there is sufficient evidence to hold the defendant. If an indictment or information has already been filed, the defendant is “handed over” for trial. If no formal accusation has been filed, the defendant is “bound over” for action by the grand jury or the prosecutor.
The preliminary hearing is not mandatory. In states where the grand jury is used, its indictment is considered a sufficient basis for requiring trial. In some states where the grand jury is not used, the prosecutor’s information is given the same effect as an indictment. This means that the defendant may be brought to trial without any preliminary hearing having been held.
The defendant in a DUI/DWI may and often does waive the right to a preliminary hearing when he is entitled to one. This may be because he intends to plead guilty anyway, or has already pleaded guilty at arraignment.