Criminal procedure is composed of the rules and processes that govern the prosecution of crime
by the criminal law system of the United States. Most criminal procedure is determined by state and local legislature, but the federal government has also formulated a criminal code, contained in Title 18 of the U.S. code. Federal criminal procedure usually addresses activities spanning state borders, or those that have some injurious impact on federal activities, such as voting or attending public school.
Criminal procedure in the United States is designed to effect a swift and efficient trial, in which society's interests are weighed against the defendant's. Accordingly, local, state and federal prosecution is limited by certain constitutional rights, outlined in the Bill Of Rights, such as the right to a trial by jury, the right to an attorney, and the right against self-incrimination, to name a few. This baseline of protection for defendants is called constitutional criminal procedure, and it differs from statutory criminal procedure, which is composed of enacted rules that govern the actual conduct of criminal trials. Statutory criminal procedure varies tremendously among different local and state jurisdictions, and is frequently revised. However, the rules of statutory criminal procedure can only ever enhance the rights bestowed upon criminal defendants, never subtract.
At the opening of criminal proceedings, the government customarily brings its charges against the defendant in one of two ways: either directly, through a Bill of Information, or by bringing evidence before a grand jury, usually composed of twenty-three members, and allowing that body to determine if trial should proceed. The federal government usually approaches criminal cases in the later manner. If the grand jury rules that the evidence against the defendant supports a case, their decision is called an indictment, and the case then goes before a petit jury (usually twelve members), or a trial by judge if the defense requests it.