The U.S. Supreme Court case Mathews, Secretary of Health, Education and Welfare v. Diaz et al., 1975 dealt with the issue of whether a federal law that denied Medicare benefits to non-U.S citizens who had not lived in the country for at least five years was constitutional or not. The plaintiffs were three elderly men from Cuba who had been denied Medicare Part B simply because they hadn't met this residency requirement. They argued that this violated their Fifth Amendment rights to equal protection under the law as well as due process. However, the Supreme Court ruled against them in a 8-1 decision stating that Congress has broad power over immigration policy and can set terms on which aliens are admitted into and remain within United States territory including imposing conditions on eligibility for public benefits such as Medicare.

In the dissenting opinion for Mathews v. Diaz, Justice William Brennan disagreed with the majority's decision to uphold a federal law that required aliens to live in the United States for at least five years before they could qualify for Medicare benefits. He argued that this requirement was discriminatory and violated equal protection principles under the Fifth Amendment of the Constitution. Brennan contended that there was no rational basis or compelling governmental interest justifying such discrimination against resident aliens who were otherwise qualified for Medicare benefits but had not lived in America long enough. He also pointed out inconsistencies within immigration laws, noting some allowed immediate eligibility while others imposed waiting periods without clear reasons behind these differences.