Recent U.S. decisions establishing a person\u27s legal sex have adopted a kaleidoscope of approaches that range from the procreative (a man must be able to fertilize ovum and beget offspring, while a woman must be able to produce ova and bear offspring), to the religious (gender is immutably fixed by our Creator at birth), to the scientific (gender itself is a fact that may be established by medical and other evidence). Under current laws and state court rulings, a male-to-female transsex person is legally a woman in approximately one-half of the states and legally a man in the other half. This Article discusses the constitutional implications of these varied approaches to determining a person\u27s legal sex. It concludes that states that refuse to recognize a transsex person\u27s sex as indicated on an amended birth certificate from a sister state violate principles of full faith and credit and unconstitutionally infringe upon the right to travel under the Dormant Commerce Clause. In addition, when states impose tests that are based on gender stereotypes and force people to live as the sex that conflicts with their self-identified sex, they violate the Fourteenth Amendment\u27s equal protection and substantive due process mandates
