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 Montana (MT), criminal procedure is governed by the Montana Code Annotated (MCA), particularly Title 46, which outlines the rules and processes for criminal justice proceedings. These procedures cover various stages such as investigation, arrest, charging, pre-trial motions, trial, and sentencing. The state's criminal procedure ensures that the rights of criminal defendants are protected, including the right to a fair trial, the right to counsel, and protections against unreasonable searches and seizures, in accordance with the U.S. Constitution and the Montana Constitution. Additionally, the Federal Rules of Criminal Procedure and relevant federal court opinions provide guidance on federal criminal matters within the state. These rules are designed to ensure that federal criminal law is enforced fairly and consistently, while safeguarding the constitutional rights of individuals. Both state and federal legal frameworks work in tandem to regulate the criminal process from the initial investigation to the final resolution of the case, whether it be conviction, acquittal, or dismissal.