Michael H. v. Gerald D., 491 U.S. 110 (1989), was a case decided by the Supreme Court of the United States involving substantive due process in the context of paternity law. Splitting five to four, the Court rejected a challenge to a California law that presumed that a married woman's child was a product of that marriage, holding that the due-process rights of a man who claimed to be a child's biological father had not been violated.