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 Idaho, criminal procedure is governed by both state statutes and the Idaho Rules of Criminal Procedure, as well as applicable federal laws and constitutional protections. These rules outline the steps and legal processes from the initial investigation of a crime to the arrest, charging, and eventual trial of a defendant. They ensure that a defendant's rights, such as the right to a fair trial, the right to counsel, and protection against self-incrimination, are upheld throughout the criminal justice process. The Fourth, Fifth, Sixth, and Fourteenth Amendments to the U.S. Constitution play a crucial role in criminal procedure, providing protections against unreasonable searches and seizures, the right to due process, and the right to a speedy and public trial by an impartial jury, among others. Idaho's criminal procedure also includes provisions for pre-trial motions, plea bargaining, and the appeals process. These procedures are designed to balance the enforcement of criminal laws with the protection of individual rights.