Felony charges such as forgery, aggravated DUI and possession of dangerous drugs are filed in the superior court on either an indictment or an information. These forms are collectively referred to as charging documents and the manner in which they are prepared is governed by Rule 13 of the Arizona Rules of Criminal Procedure. When a felony case is initiated in court it must first go through a probable cause determination before the matter can be set for trial. There are two different forms in which this can occur.
The first is called a grand jury this is where the prosecution presents the case to a group of citizens outside the presence of the defendant and the grand jurors are asked to determine whether probable cause exists based on the evidence presented to them by the prosecution. If the grand jury finds probable cause they return an indictment which then becomes the charging document in that particular case.
Alternatively a felony charge can be initiated through a preliminary hearing which is conducted in a manner very similar to that of a trial however during a preliminary hearing there is no jury rather a judge is the fact finder and the burden of proof is much lower than that ordinarily required at a criminal trial. At a criminal trial when a person could potentially be imprisoned if convicted our constitution requires that the prosecution provide proof beyond a reasonable doubt before that can occur. During a preliminary hearing however the prosecution is required only to demonstrate that probable cause exists for the case to move forward in the court system. If a preliminary hearing is held and the judge finds probable cause the state is permitted to file a document called an information which would be used as the charging document throughout the remainder of that case.
Because felony cases involving indictments are initiated through the grand jury where neither the defendant nor the defense attorney are present the prosecutor has special obligations to present the evidence in a fair and impartial manner and present evidence that is clearly exculpatory meaning that it tends to show that the person accused is not guilty. If the prosecutor fails to present the evidence to the grand jury in this manner the case could be remanded to the grand jury for a re‑determination of probable cause.
Although the grand jury was once reserved for more serious cases like second degree murder
and sexual conduct with a minor
the Maricopa County attorney's office has been utilizing the grand jury much more broadly over the past three years and typically sends less-serious felony cases through that process including those involving allegations of possession of Marijuana