The social science testimony proved to be one of the most enduring aspects of the case. The argument that segregation itself causes harm — independent of whether the separate facilities are of comparable physical quality — would carry forward through subsequent civil rights litigation. It would appear, refined and elaborated, in the arguments the NAACP made in Brown v. Board of Education.
## Judge McCormick’s Constitutional Reasoning
Paul J. McCormick had served as a Republican member of Congress from California before his appointment to the federal bench. His background did not mark him as an obvious champion of civil rights claims; the federal judiciary of this period was not, in general, friendly territory for such arguments. His ruling in Mendez v. Westminster was therefore both surprising in some respects and historically significant.
McCormick’s opinion, issued February 18, 1946, worked through the school districts’ justifications and found them wanting. The English-language justification — that Mexican American children needed separate instruction because of their linguistic situation — failed because the evidence showed that placement was based on ancestry and surname, not language ability. Many of the children being sorted into Mexican schools spoke English perfectly well. The districts could not establish that language need actually drove their assignment decisions.
On the physical conditions question, McCormick declined to resolve the case by simply comparing buildings and declaring one side winner. His opinion instead advanced a broader principle: that nominally equal physical resources in separate schools did not satisfy the requirements of equal protection. “A paramount requisite in the American system of public education is social equality,” he wrote. Public education, he stated, must “be open to all children by unified school association regardless of lineage.”