Law enforcement agencies operate at all levels, including government-local, county, state, country, and even multi-national or international. Law enforcement jurisdiction is determined by federal or state laws within a country and by international treaties or agreements for multi-national or international agencies. In many cases, more than one agency will have jurisdiction at the same time; however, one of the agencies generally has the authority to usurp authority from the other law enforcement agencies.
Within most countries, there are local law enforcement agencies, as well as national or federal agencies. In the United States, for example, each state has a variety of law enforcement agencies, such a city or town police department, county sheriffs departments, and state police. Typically, the city police will have jurisdiction within the legal boundaries of the city, while the sheriff will handle issues outside the boundaries of the city but within the county. The state police often maintain jurisdiction of all state roadways, although they may technically have jurisdiction over the entire state of they wish to exercise it. The state legislature in each state determines law enforcement jurisdiction within their state.
Federal or national law enforcement jurisdiction is commonly determined by a constitution or the national legislature. In some cases, the national law enforcement agency handles serious matters that are referred to it by local agencies, as is the case in Australia, for instance. In the United States, federal law enforcement agencies are charged with investigating crimes that have a multi-state component. The Drug Enforcement Agency (DEA), for example, investigates major drug trafficking operations, while the Federal Bureau of Investigation (FBI) investigates bank robberies and kidnappings when the victim is transported across state lines.
International law enforcement jurisdiction is frequently the result of formal treaties or informal cooperation among many countries. Often, the role of an international law enforcement agency is that of a clearinghouse for information. The International Criminal Police Organization (INTERPOL), for example, acts as a central repository for information on criminal investigations that cross national boundaries, such as international money laundering or terrorism. INTERPOL operates under a constitution that member states agree to abide by at all times.
In some instances, law enforcement jurisdiction is shared by more than one agency. At times, jurisdictional issues can become complicated and actually hinder the investigation and prosecution of crimes. Within the United States, there are a number of areas where a tribal, state, and federal law enforcement agency could invoke jurisdiction over a crime. Sometimes the issue is resolved by agreement between the agencies, while, in other cases, a defendant may find himself or herself charged with the same crime in more than one court.