The Supreme Court’s 1954 decision in Hernandez v. Texas was a legal watershed for Mexican Americans in the United States. In that decision, the nation’s highest court ruled that the systematic exclusion of persons of Mexican ancestry from juries in Jackson County, Texas violated the Constitution. The evidence of exclusion included the fact that no person of Mexican ancestry had served on a jury in that county in the previous 25 years even though Mexicans comprised more than 10 percent of the adult population. (from Introduction)
This article by Kevin R. Johnson gives some important legal contexts to the events following the Zoot Suit Riots and advances in the civil rights of Mexican-Americans.