In Rivera v. Minnich (1986), the U.S Supreme Court ruled that a state does not violate due process by presuming, in child support proceedings, that a man is the father of a child born out of wedlock if he fails to appear for blood tests. The case involved an unmarried couple where the woman sought financial assistance from her ex-partner for their alleged son's upbringing. The defendant did not comply with court-ordered blood tests to establish paternity and was subsequently presumed as the biological father under Pennsylvania law. He challenged this presumption arguing it violated his constitutional rights to due process and equal protection under Fourteenth Amendment since it shifted burden of proof onto him without clear evidence of paternity. However, the Supreme Court upheld lower courts' rulings stating such laws were designed to protect welfare interests of children born outside marriage and did not infringe upon defendants' constitutional rights.

In the dissenting opinion for Rivera v. Minnich, Justice Brennan disagreed with the majority's decision to uphold Pennsylvania's paternity law that required corroboration of a mother’s testimony in order to establish paternity. He argued that this requirement was discriminatory and violated equal protection principles as it singled out unwed mothers for different treatment without any justification. Furthermore, he contended that such laws perpetuated harmful stereotypes about women being untruthful or unreliable witnesses, particularly in matters related to their sexual behavior. Additionally, he pointed out how these laws disproportionately affected poor women who might not have access to other forms of evidence like medical records or witness testimonies due to financial constraints or social stigma associated with non-marital sex and childbirth.