Marcus filed the suit on March 2, 1945, in the United States District Court for the Southern District of California, in Los Angeles. The case was captioned Mendez et al. v. Westminster School District of Orange County et al. and named the four school districts and their superintendents as defendants. It argued that approximately 5,000 children of Mexican and Latin descent were being denied the equal protection of the laws guaranteed by the Fourteenth Amendment.
The legal argument was carefully constructed. Marcus expanded the individual enrollments into a class action that made the scope of the harm explicit: this was not a dispute about one family’s children but about a countywide practice affecting thousands of students. The constitutional hook was the Fourteenth Amendment’s equal protection clause, which bars states from denying any person within their jurisdiction the equal protection of the laws.
The school districts, represented by Orange County counsel Joel Ogle, made arguments that were standard for the period. They contested whether federal courts had jurisdiction over what they framed as a state educational matter. They argued that separate schools had been created to address the special instructional needs of Spanish-speaking students who required a different educational approach to acquire English. They insisted the practice was pedagogical, not discriminatory.
The jurisdictional argument was legally serious — the relationship between federal courts and state education systems was genuinely contested in this period. But the pedagogical defense had a problem that would become visible in court: it did not survive scrutiny of what actually happened in the schools.