H married W in 1959 during H's three-day stopover in California in route from a military base in Texas to a tour of duty in Korea. At the time of the marriage, both parties were domiciled in New York and immediately following the marriage and war both returned to New York. After the ceremony, W returned home to New York while H defended the free world. Darwin was born in New York in 1961, and Ilsa was born the next year; both in New York. In March 1972, the Kulkos separated. W moved to San Francisco, and a written separation agreement was drawn up and signed in New York. The children would remain with H during the school year but would spend Christmas, Easter, and summer vacation with W. H agreed to pay $3,000 per year in child support to W. W waived any claim for her own support. W flew to Haiti and procured a divorce decree that incorporated the terms of their separation agreement. W then went to California, remarried, and took the name Horn. In 1973, Ilsa decided she wanted to remain in California with her mother after the vacation, and the same happened with Darwin in 1976. W then sought a California court to award her full custody of the children and child support. H moved to quash service, as he was not a resident of California and lacked sufficient minimum contacts under International Shoe. The California Supreme Court sustained the assertion of jurisdiction over H based on the benefits to H of his daughter being there and his purchase in New York of an airplane ticket to California. H appealed to the Supreme Court. The Supreme Court granted certiorari.