Was there a court ruling?
Through the force of sheer numbers, the English-speaking American settlers entering the Southwest established their language, culture, and law as dominant, to the extent it fully displaced Spanish in the public sphere; this is why the United States never developed bilingualism as Canada did. For example, the California constitutional convention of 1849 had eight Californio participants; the resulting state constitution was produced in English and Spanish, and it contained a clause requiring all published laws and regulations to be published in both languages. The constitutional convention of 1872 had no Spanish-speaking participants; the convention's English-speaking participants felt that the state's remaining minority of Spanish-speakers should simply learn English; and the convention ultimately voted 46-39 to revise the earlier clause so that all official proceedings would henceforth be published only in English.