The vast majority of criminal prosecutions take place in state courts. The sections below highlight some of the key differences between state and federal criminal systems.
A state has jurisdiction over defendants who violate the laws of that state—the power to arrest, charge, try, and convict them. The federal government has power over defendants who commit criminal acts on federal property (for example, an assault in a national park) or whose criminal acts cross state lines (for example, a kidnapper who transports a victim from Iowa to Missouri). The federal government also has jurisdiction over a group of federally defined crimes, such as offenses related to immigration fraud and U.S. customs violations.
A state and the federal government can have "concurrent" power over a defendant when the same criminal activity violates both state and federal laws (for example, selling drugs or robbing banks). In those situations, state and federal prosecutors make case-by-case decisions as to whether a defendant will be prosecuted in state or federal court.
State and local law enforcement officers enforce and investigate violations of state law within their territorial jurisdiction—usually a municipality, city, county, or state. They are often organized into city or municipal police departments, county sheriff offices, and state patrol or investigation units.
Federal agencies with law enforcement authority enforce and investigate only federal crimes that fall within their agency's purview. For example, Drug Enforcement Administration (DEA) agents investigate federal drug crimes, and Immigration and Customs Enforcement (ICE) agents enforce federal immigration laws. The FBI can investigate any federal crime that doesn't fall under the exclusive jurisdiction of another federal agency.
Federal criminal prosecutions are handled by U.S. attorneys, who are appointed by and ultimately responsible to the U.S. Attorney General. State prosecutors—sometimes called district, state, county, or city attorneys—prosecute violations of state and local law. Depending on the state, the head prosecutor for the city, county, district, or state might be elected or appointed to the position.
Most criminal defendants qualify for government-paid defense attorneys. Government-paid attorneys are usually employed either by an office of the Federal Public Defender or a state or county public defender office, although localities in some states maintain a list of private attorneys, paid by the government, in place of an office of public defenders. If a public defender office cannot handle the case due to insufficient staffing, or because the office already represents a co-defendant, the court will appoint a private attorney, often called a "panel attorney," who is paid by the court to represent the defendant.
Most federal criminal prosecutions occur in United States District Courts. State criminal prosecutions are handled in local or state courts that carry titles, such as "superior court," "municipal court," "district court," or "county court," depending on the state and the seriousness of criminal charges.
Federal trial judges are known as District Court judges; they are appointed for life by the President, subject to confirmation by the U.S. Senate. State court judges are typically initially appointed by governors and then are subject to election every few years. State court trial judges carry titles such as Superior Court Judge, Municipal Court Judge, and (in New York) Supreme Court Judge. In both state and federal courts, magistrates may preside over pretrial hearings such as bail hearings, as well as less serious criminal trials.
Federal courts use the "all-purpose judge" system. This means that the same judge almost always presides over a case from beginning to end—that is, from a defendant's first court appearance to final acquittal or sentencing. Some states also follow the all-purpose judge model. In many states, however, judges are specialized. For example, one judge may determine bail, another judge may hear pretrial motions, and a third judge may preside over a trial.
A person convicted in state court and sentenced to imprisonment might spend time in local jail or state prison. Jails are short-term lockups, typically run by a city or county, that house pretrial defendants, inmates serving a misdemeanor sentence, and inmates serving time in jail as a condition of felony probation. State prisons handle long-term confinement of inmates serving felony sentences (usually more than one year).
A person convicted in federal court falls under the correctional authority of the Federal Bureau of Prisons (BOP). After sentencing, the BOP determines where to house offenders based on security and program needs. The BOP does not have a state jail equivalent for offenders serving short-term sentences but will often contract with a local jail to house a federal inmate with less than a year to serve.