If jurisdiction in the case is in personam or quasi in rem (over a person or property or a debt owed by a person), the court may not exercise that jurisdiction unless the defendant has "minimum contacts" with the state in which the court sits (the forum state). Generally, the requirement of minimum contacts means that the defendant has to have taken actions that were purposefully directed towards the forum state. Such actions may include, among others, selling goods in the state, being incorporated in the state, visiting the state, or bringing property in the state. In order to exercise jurisdiction, such minimum contacts are required by the defendant's Fourteenth Amendment federal constitutional right to due process.
Even if the defendant's miniumum contacts with the forum state are found to exist, the court will not exercise jurisdiction if considerations of "fair play and substantial justice" would require making the defendant defend in the forum state so unreasonable as to constitute a due process violation.
Minimum contacts can consist of either some type of systematic and continuous contact with the forum ("general jurisdiction"), or isolated or occasional contacts purposefully directed toward the forum ("specific jurisdiction"). A single contact can suffice to establish personal jurisdiction, but where jurisdiction is based on a single contact, the nature and quality of the contact is determinative. The principal test of foreseeability in a due process analysis "is that the defendant's conduct and connection with the forum state are such that he should reasonably anticipate the possibility of defending a suit in the forum. A defendant cannot reasonably anticipate out-of-state litigation unless he has purposefully availed himself "of the privilege of conducting activities within the forum State, thus invoking the benefits and protections of its laws. In cases in which the litigants are from foreign countries, a court must also consider the policies of the foreign countries, as well as U.S. foreign policy, in determining whether exercising jurisdiction would be fair.
Some of the factors which may be examined, among others, to determine whether minimum contacts exist include: (1) the quantity of contacts with the state, (2) the nature and quality of those contacts, (3) the connection or relationship between the contacts and the cause of action, (4) the state's interest in providing a forum, and (5) the relative convenience of the parties.
Examples that usually are considered to be minimum contacts include any kind of contract or business practice with a member within the territory, such as insurance contracts sold in a particular locale. Those that are not considered of interest would be advertising. The important exception has been Internet advertising which some courts have found sufficient to apply the minimum contacts principle.