Criminal procedure is the process related to the investigation, arrest, charging, and conviction or acquittal of a criminal defendant. Much of criminal procedure is comprised of processes and rules through which the government (state, federal, or municipal) enforces substantive criminal law and through which a criminal defendant’s Constitutional and other rights are protected.

The law of criminal procedure is primarily located in the applicable state or federal rules of criminal procedure and state and federal court opinions interpreting and applying Constitutional and other legal rights.

In New Jersey, criminal procedure is governed by a combination of state statutes, the New Jersey Rules of Court, and federal laws, particularly the U.S. Constitution. The process begins with an investigation and can proceed to an arrest, whereupon the accused is informed of their rights (Miranda rights). Following an arrest, charges are filed, and the defendant is arraigned where they plead guilty or not guilty. Pretrial motions, discovery, and plea negotiations may occur before a case goes to trial. At trial, the defendant has constitutional rights, including the right to a fair and public trial, the right to be tried by an impartial jury, the right to be presumed innocent until proven guilty beyond a reasonable doubt, the right to confront witnesses, and the right to an attorney. If a defendant cannot afford an attorney, one will be provided by the state. After a trial, there may be a conviction or acquittal, and the right to appeal exists if there is a conviction. New Jersey's criminal procedure also includes provisions for post-conviction relief under certain circumstances. These procedures are designed to ensure that a defendant's rights are protected throughout the criminal justice process.