A long arm statute is a law whereby the courts of a forum state (the state where the suit is brought) may obtain jurisdiction of a person in another state if the action that is the basis of the lawsuit grew out of a transaction in which the defendant was in, or doing business in, or had an interest (such as land) in, the forum state. Before the days of long-arm statutes, ordinarily a court in a forum state had jurisdiction only over people within the confines of the forum state.
Some states hold that if a manufacturer puts goods into the stream of interstate commerce with the probability that some of those goods will eventually be sold in the forum state, long-arm jurisdiction should be granted. Other states hold that if the manufacturer could not have anticipated that his goods would reach the forum state, then long-arm jurisdiction should be denied.