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 Wisconsin, criminal procedure is governed by both state statutes and federal law, which outline the processes and rules for the investigation, arrest, charging, and trial of individuals accused of crimes. The Wisconsin Statutes, specifically Chapters 967 to 975, provide detailed procedures for various stages of the criminal process, including initial appearances, preliminary hearings, arraignment, motions, trials, and sentencing. These procedures are designed to ensure the fair administration of justice and to protect the constitutional rights of defendants, such as the right to due process, the right to a speedy and public trial, and the right to counsel. Additionally, the Federal Rules of Criminal Procedure and the U.S. Constitution, particularly the Fourth, Fifth, Sixth, and Fourteenth Amendments, play a crucial role in shaping criminal procedure in Wisconsin. Court opinions from both state and federal courts interpret and apply these laws and constitutional provisions to specific cases, further refining the body of criminal procedure law.