The King v. Smith case in 1967 was a landmark decision by the US Supreme Court that struck down Alabama's "man-in-the-house" rule, which denied aid to children who were deemed illegitimate because their mothers cohabitated with men. The court ruled that this policy violated the Equal Protection Clause of the Fourteenth Amendment and contradicted federal law governing Aid to Families with Dependent Children (AFDC). This ruling established an important precedent for welfare rights, asserting that states could not impose additional eligibility requirements on federally funded programs beyond those set by Congress. It also reinforced the principle of national supremacy over state laws in matters related to social welfare policies.

In the dissenting opinion for King v. Smith, Justice Harlan disagreed with the majority's interpretation of federal law and its application to Alabama's "substitute father" regulation. He argued that states should have discretion in determining eligibility requirements for welfare benefits under Aid to Families with Dependent Children (AFDC). He believed that Congress intended for states to have flexibility in administering AFDC programs, including setting their own standards of need and methods of investigation. Furthermore, he contended that the Court overstepped its bounds by interpreting federal law instead of deferring to administrative expertise at both state and national levels. In his view, this case was not about constitutional rights but rather a dispute over statutory construction which should be resolved through legislative or administrative channels rather than judicial intervention.