How Does a Criminal Case Go Through the Justice System?

Here's how to criminal process works. From investigation to arrest to a criminal charge and resolution.

By , Attorney · UC Law San Francisco

How does a criminal case begin, progress, and end? This article explains the typical life cycle of a criminal case. Some cases are simple, and others include many twists and turns. You should consult an attorney to discuss how the general information discussed here applies to your case.

1. Investigation

An incident that becomes the focus of a criminal case usually begins with an investigation by an officer in a law enforcement agency, such as the Federal Bureau of Investigations (FBI), local police department, or county sheriff.

An investigation could begin when an officer observes a situation, such as a car weaving in its lane, that could involve a violation of the law. Suspecting that the driver is under the influence, the officer would observe the driver's behavior and use field sobriety tests to gather evidence of intoxication. The officer could also take a breath or blood sample to test for blood alcohol content.

Investigations can also begin when a victim or witness reports a suspected crime. In these cases, officers will interview witnesses and collect physical evidence (like fingerprints, carpet fibers, and bullet casings) and biological evidence (such as blood, hair, and bodily fluids).

Officers document their investigations with photographs, videos, and written reports that they submit to prosecutors. See below for a discussion of how prosecutors use the evidence gathered by investigators to make charging decisions.

2. Arrest

An arrest occurs when a person, usually a law enforcement officer, uses legal authority to restrict a suspect's freedom of movement. Probable cause is the key issue in the arrest process. The police need probable cause to make an arrest or obtain an arrest warrant from a judge.

Generally, probable cause requires more than mere suspicion that a suspect committed a crime but not proof beyond a reasonable doubt. Probable cause is a reasonable belief in the suspect's guilt, based on the facts and information prior to the arrest.

Judges decide whether there is probable cause to issue an arrest warrant on a case-by-case basis. To make a lawful arrest without an arrest warrant, officers must not only have probable cause, but they must prove that the arrest was immediately necessary.

A person who is not a sworn officer may make a citizen's arrest, but valid citizen arrests are rare. The civilian typically must witness a perpetrator commit a misdemeanor, or have reasonable cause to believe the perpetrator committed a felony. People should exercise care if they decide to make an arrest. A wrongful arrest could lead to criminal charges and a civil lawsuit for battery and false imprisonment.

3. Charging a Crime

As discussed above, officers summarize their investigations in reports and present those reports and related evidence to prosecutors. Prosecutors review the reports and decide what, if any, criminal charges to file.

Prosecutors describe the criminal charges against a person and the factual basis for those charges in a charging document filed with the court. Charging documents are called "complaints," "informations," and "indictments."

In the federal system, the U.S. Constitution requires that for potential felony charges, a prosecutor must present the evidence to an impartial group of citizens called a grand jury. The grand jury listens to the evidence. If the grand jury concludes that there is probable cause to believe that an individual committed a crime, the grand jury will issue a charging document known as an indictment.

The grand jury is a constitutional requirement only for felony crimes prosecuted by the federal government. States have grand juries, which prosecutors sometimes use, but more frequently, prosecutors initiate court proceedings by way of a complaint. Once the prosecutor has obtained an indictment, or written a complaint or information, a judge will issue an arrest warrant for the defendant.

A felony complaint typically requires a preliminary hearing in front of a judge. In most states, if the court decides after the preliminary hearing that there is probable cause to believe the defendant committed the crimes alleged in the complaint, the court will advance the case. See below for more information about preliminary hearings.

Both an indictment and a typical information signify a finding by a neutral third party (grand jury or judge) that there is a factual basis for criminal charges.

4. Initial Hearing or Arraignment

Shortly after defendants are arrested and charged (typically within 48 hours), they appear before a judge for an initial hearing on the case. In some states, these initial hearings are called arraignments.

At an initial hearing or arraignment, defendants learn more about their rights and the charges against them. The court might also:

5. Discovery

Discovery is the process through which defendants and prosecutors find out about the other side's case. Historically, prosecutors weren't entitled to information about a defendant's case. But in recent years, discovery statutes require a two-way exchange of evidence in an effort to determine the truth, save court time, and protect victims and witnesses.

Examples of discovery material include police reports, witness statements, photographs, videos, and any other information that the parties plan to use at trial. The U.S. Constitution requires prosecutors to provide the defense with any evidence that might hurt the prosecution's case, called exculpatory evidence.

6. Plea Bargaining

Plea bargaining is the most common way criminal cases are resolved. A plea bargain is an agreement between the defendant and the prosecution to resolve a criminal case without going to trial. Most commonly, the defendant agrees to plead guilty or no contest to one or more of the charged offenses, and the prosecutor agrees to dismiss or reduce the remaining charges or recommend a lighter sentence, or both.

In most jurisdictions, plea bargaining can take place any time after the defendant has been charged, up to and including the morning of the trial (the defendant can even plead mid-trial).

7. Preliminary Hearing

Defendants who plead not guilty to felony charges are entitled to preliminary hearings in most states. Defendants charged with misdemeanors or by grand jury indictment are not entitled to preliminary hearings.

Preliminary hearings are like a mini-trial. Prosecutors must present enough evidence to convince the judge that there is probable cause (enough objective evidence) to require the defendant to stand trial for the crimes charged in the complaint.

If the judge decides that there's probable cause, the prosecutor files an information and the case proceeds to trial. If the judge decides that there is not probable cause to believe the defendant is guilty, the court will dismiss the charges.

8. Trial

The right to a jury trial in all felony and most misdemeanor criminal cases is guaranteed by the Sixth Amendment of the U.S. Constitution, as well as the laws of every state. The defendant can decide to waive a jury and allow a judge to decide the case.

Jury trial procedures vary depending on which court is hearing the case, but most trials begin with jury selection when both sides select six to 12 jurors from a pool of potential jurors. After jury selection, the prosecutor and defense attorney give the jury a preview of the evidence in their opening statements.

After opening statements, the prosecution presents its evidence, which might include witness testimony, physical evidence (such as a murder weapon or fingerprints), photographs, and video and audio recordings. Then, the defense has a chance to present its evidence. Each side can cross-examine the other side's witnesses.

After the prosecution and defense have finished with their presentations, the judge instructs the jury on the law that applies to the case. The lawyers use their closing arguments to try to convince the jurors to vote in their favor. Finally, the jury deliberates and tries to reach a verdict of guilty or not guilty. If less than the required number of jurors agree on a verdict, the jury is "hung." The prosecution can dismiss the case, enter into a plea bargain, or try the case again.

9. Sentencing

If the jury finds the defendant guilty or the defendant pleads guilty or no contest, the court sentences the defendant. Sentencing can happen at a sentencing hearing or at the time a defendant enters a plea of guilty or no contest.

Federal and state laws set the punishments for most crimes. Typical penalties include fines and jail or prison time. Sentencing laws can specify exact incarceration terms and fines, or give judges a range from which to choose. Judges might also have discretion to impose probation instead (a person who accepts probation must abide by specific terms and conditions, such as attending school and regular check-ins with a probation officer).

When they have some leeway, judges consider a variety of factors when they craft a sentence. Factors include the defendant's criminal record, the nature of the crime itself, the amount of loss or damage caused by the defendant, whether the defendant has expressed regret for the crime, and statements from victims.

10. Appeal

A guilty verdict is not necessarily the end of a criminal case. Even after conviction, a defendant can file an appeal, asking a higher (appellate) court to review and change a decision of a lower court. A defendant can appeal the conviction or appeal just the sentence. With defendants who are sentenced following a plea bargain, part of the bargain might include a waiver of the right to appeal.

An appeal is not another trial; rather, it is an opportunity for a defendant to argue that certain errors committed by the trial judge or the defendant's own attorney likely changed the outcome of the case. For instance, a defendant might argue that the judge's decision to deny the defense's motion to suppress evidence was not only incorrect but likely changed the outcome of the case. In a variation of "no harm, no foul," an appellate court will not reverse a conviction based on a mistake in the trial court unless the appellate judges are convinced that the mistake was a significant factor in the jury's decision.

An appellate court that sides with the defense can reverse a conviction, alter a sentence, or order a new trial altogether. In rare cases, the appellate court will dismiss the case altogether.

Always Talk to an Attorney

If you are facing criminal charges, seek advice from an experienced criminal defense attorney right away. A knowledgeable attorney will be able to explain the specific court procedures in your jurisdiction.

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