A criminal case usually gets started with a police arrest report. The prosecutor then decides what criminal charges to file, if any. Some cases go to a preliminary hearing, where a judge decides if there is enough evidence to proceed. Cases can also start when a grand jury issues a criminal indictment.
After an arrest, the police report goes to a prosecutor whose job it is to initiate cases. An arrest report summarizes the events leading up to the arrest and provides numerous details, such as dates, times, locations, and witness names.
The prosecutor will typically:
After an arrest, the police officer specifies the crime or crimes that made the basis for the arrest. Officers may recommend that the prosecution file additional charges, too. But prosecutors get to make the ultimate decision on what the charges will be.
A defendant typically learns what the formal charges will be at the first court appearance. But prosecutors' initial charges are subject to change. For example, a prosecutor might not make a final decision on what charges to file until after a preliminary hearing, which may take place more than a month after arrest.
Typically, if the prosecutor decides to file a felony complaint rather than present the case to a grand jury, the defendant is entitled to a preliminary hearing. At that hearing, the prosecutor must show that the state has enough evidence of the defendant's guilt to warrant a trial.
But normally, if the case proceeds by grand jury indictment, no preliminary hearing need be held.
For much more on this stage of a case, see our section on Preliminary Hearings.
If a felony is involved, prosecutors sometimes leave it to grand juries to decide whether charges should be filed. Grand juries are similar to regular trial juries (called "petit juries") in that they are made up of randomly selected individuals. The grand jurors listen to the evidence and decide whether charges should be brought against an individual—that is, they decide whether to indict someone.
Unlike petit juries, which sit on only one case, grand juries may address many cases in the course of their service. In fact, serving on a grand jury can mean a time commitment of six months or longer.
Here are other ways grand juries are different:
When bringing a case to a grand jury, the prosecutor presents the jurors with a "bill" (the charges) and introduces evidence—usually the minimum necessary, in the prosecutor's opinion—to secure an indictment. The proceedings are typically secret; it is standard practice to call witnesses to testify against the suspect without the suspect or the suspect's lawyer present. But, depending on state law, indicted suspects might later be able to get transcripts or recordings of grand jury proceedings. (The availability of a transcript is a big reason why prosecutors like to keep the evidence to the minimum.)
Prosecutors may advise the suspect that they are the target of the grand jury investigation (but they don't have to). In the federal system, when prosecutors have substantial evidence that the suspect committed a crime, they may send the suspect what's called a "target letter." The target letter generally notifies the suspect of the suspected criminal violations and may invite the suspect to testify before the grand jury. However, most suspects will refuse to testify by invoking their privilege against self-incrimination under the Fifth Amendment to the U.S. Constitution.
If the grand jury decides to indict, it returns what is called a "true bill." Otherwise, it returns a "no bill." But even if the grand jury returns a no bill, the case isn't necessarily closed. Again depending on the law in the jurisdiction, the prosecutor might be free to return to the same grand jury with more evidence, present the same evidence to a second grand jury, or bypass the grand jury altogether and file a criminal complaint (or other charging document.)
Charging procedures can differ significantly between federal and state courts, from one state to another, and even between locales within the same state. If you've been arrested, consult an experienced criminal defense attorney. Such a lawyer should be able to explain the applicable law and guide you through the process.