A 1941 segregated school for children of Mexican descent, photo by the USDA
"The equal protection of the laws' pertaining to the public school system in California is not provided by furnishing in separate schools the same technical facilities, text books and courses of instruction to children of Mexican ancestry that are available to the other public school children regardless of their ancestry. A paramount requisite in the American system of public education is social equality. It must be open to all children by unified school association regardless of lineage."
-Federal District Judge, Paul J. McCormick, from Mendez v. Westminister School Dist. of Orange County, 64 F.Supp. 544 (D.C.CAL. 1946).
Seven years before Brown v. the Board of Education, there was Mendez v. Westminster. This 1946 case that went all the way to the Supreme Court started with five Mexican American Fathers: Thomas Estrada, William Guzman, Gonzalo Mendez, Frank Palomino, and Lorenzo Ramirez. Their complaint was simple; children of Mexican descent were unfairly being segregated into 'schools for Mexicans' in several school districts in Orange County. The argument for the case was that this segregation constituted a violation of the equal protection clauses of the Fourteenth Amendment, as the students were being discriminated against due to their ancestry.
As you can see from the quote above, the district judge ruled that it indeed was a violation of the 14th amendment, which would have been highly resonant in terms of segregation cases. Sadly, this was not to set a precedent that would do away with all school segregation (That would have to wait until Brown v. the Board of Education, mentioned previously). Instead, when appealed to the Supreme Court, the highest court in the nation instead ruled that the segregation of Mexican and Mexican-Americans wasn't allowed because California law only allowed Mongolians, Chinese, and Japanese people to be segregated. Thankfully it wasn't long until 1947, when California passed law that did away with all educational segregation in the state. The nation, however, would still have longer to wait for educational equality.
If you're looking for more information on this little-known but important case, check out this NPR story, or this link to information from the National Park Service. The Texas Bar has also put together an excellent site for information about the case.