International Shoe Co. v. Washington, 326 U.S. 310 (1945), was a landmark decision of the Supreme Court of the United States in which the Court held that a party, particularly a corporation, may be subject to the jurisdiction of a state court if it has "minimum contacts" with that state. The ruling has important consequences for corporations involved in interstate commerce, their payments to state unemployment compensation funds, limits on the power of states imposed by the Due Process Clause of the Fourteenth Amendment, the sufficiency of service of process, and, especially, personal jurisdiction. Facts The plaintiff, the State of Washington, established a tax on employers conducting business therein with the stated legislative purpose of providing a fund to be used for financial assistance to newly unemployed workers in the state. The tax was in effect a mandatory contribution to the state's Unemployment Compensation Fund. The defendant, International Shoe Company, was an American company that was incorporated in Delaware with its principal place of business ("PPB") in Missouri. The corporation had maintained for some time a staff of 11-13 salesmen in the State of Washington, working on commission. The salesmen were residents of that state and they met with prospective customers in motels and hotels, and occasionally rented space to put up displays. The company thus had no permanent "situs" of business in the State. Each year, the salesmen brought in about $31,000 in compensation. International Shoe's solicitation system allegedly was set up explicitly to avoid establishing the situs of the business in other states insofar as the salesmen did not have offices, did not negotiate prices, and sent all orders back to Missouri; shipments from the plant to customers were sent f.o.b. Procedural history International Shoe Co. did not pay the tax at issue in this case, so the state effected service of process on one of their salesmen with a notice of assessment. Washington also sent a letter by registered mail to their place of business in Missouri. International Shoe made a special appearance before the office of unemployment to dispute the state's jurisdiction over it as a corporate "person." However, the trial court ruled that it had personal jurisdiction over the defendant corporation. This ruling was upheld in the appeal tribunal, the Superior Court, and the Supreme Court of Washington. International Shoe Co. then appealed to the U.S. Supreme Court. Ruling The issue involved a determination of