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 York, criminal procedure is governed by the New York Criminal Procedure Law (CPL), which outlines the processes and rules for the conduct of criminal trials, from the initial investigation to the final disposition of a case. This includes procedures for arrest, search and seizure, arraignment, discovery, plea bargaining, trials, and appeals. The CPL aims to ensure that the constitutional rights of individuals, such as the right to a fair trial, the right to counsel, and protection against self-incrimination, are upheld throughout the criminal justice process. Additionally, federal rules and constitutional protections, such as those provided by the Fourth, Fifth, Sixth, and Fourteenth Amendments to the U.S. Constitution, apply to all states, including New York. These federal laws and constitutional rights work in conjunction with state laws to ensure that criminal defendants receive due process and are protected from unlawful searches and seizures, coerced confessions, and other violations of their rights.