Territorial jurisdiction is a jurisdictional responsibility that is established by geography. It is primarily a United States law concept, though variations of the concept have been adopted by other nations. In the United States, it impacts local, state and national court systems and is required for the legal prosecution of a case under United States law. Judgments rendered by courts that do not have territorial jurisdiction are unenforceable.
While territorial jurisdiction is the primary consideration when determining which court will hear a case, it can be superseded by both subject-matter jurisdiction and personal jurisdiction. Subject-matter jurisdiction applies to a court's right to hear cases about specific subjects, regardless of where the case occurs. Personal jurisdiction applies to a court's right to hear cases concerning specific people, regardless of where the people were when the alleged crime or offense was committed or where they are at the time of the hearing. A court cannot assert subject-matter or personal jurisdiction if it does not also have territorial jurisdiction.
For example, a murder committed in New York City is prosecutable by the City of New York, the territory in which the crime was committed. If, however, the murder was committed as part of an act of terrorism, the United States government can assert its right to prosecute the case because it has subject-matter jurisdiction over terror crimes and also has territorial jurisdiction because the crimes occurred within the United States. Similarly, if an active-duty army officer committed the murder, the United States army can assume responsibility for the case because it has personal jurisdiction over the officer and also has territorial jurisdiction as an extension of the United States government.
Territorial jurisdiction can become confusing when more than one geography is involved. If a string of bank robberies crosses the boundaries between two or more local jurisdictions within the same US state, each individual robbery may be prosecuted by the geographic jurisdiction in which it was committed or the state court may prosecute all of the crimes at once. If a crime crosses state lines, such as is the case when stolen goods are transported between states, the federal government will most likely prosecute the case because all aspects occurred within the United State's geographical boundaries.
A crime does not have to be committed within the country in order for the United States to have territorial jurisdiction. The United States also has jurisdiction in cases occurring on the grounds of foreign embassies, on the grounds of United States military bases in foreign countries and on vessels that are sailing under a United States flag. It may also claim jurisdiction in areas that are part of the international commons, which include Antarctica, the high seas outside of coastal territories and outer space.