In the case of Harris, Secretary of Health and Human Services v. Rosario et al., 1979, the U.S Supreme Court ruled that a federal statute providing lower welfare benefits to residents of Puerto Rico than to residents in the mainland United States did not violate the Fifth Amendment's Due Process Clause. The plaintiffs argued that this differential treatment was unconstitutional as it discriminated against citizens living in Puerto Rico. However, Congress justified its decision by citing legitimate reasons such as differences in living costs between Puerto Rico and mainland states and also because federal income taxes were not collected from residents on the island. The court held that these justifications were rational enough for differentiating benefit levels under Aid to Families with Dependent Children (AFDC) program thereby upholding Congress' power over territorial affairs.

In the dissenting opinion for Harris v. Rosario, Justice Marshall argued that the lower standard of scrutiny applied by the majority was inappropriate given that this case involved a federal statute discriminating against citizens based on their place of residence. He contended that such discrimination should be subject to strict scrutiny as it infringes upon fundamental rights and creates unequal treatment among American citizens. Furthermore, he disagreed with the majority's assertion that providing less aid to Puerto Rico due to its exemption from certain federal taxes was justified; instead, he believed this reasoning failed to consider whether these tax exemptions actually compensated for reduced benefits. Lastly, Justice Marshall expressed concern about how this ruling could set a precedent allowing Congress to discriminate between different groups of U.S citizens without sufficient justification.