Note that in many states, caste and other ancestry discrimination is unambiguously protected. There have been any number of suits claiming the Civil Rights Act

Note that in many states, caste and other ancestry discrimination is unambiguously protected. There have been any number of suits claiming the Civil Rights Act prohibits caste-based discrimination; I don't think there are any high-level rulings about whether it does, but the basic argument doesn't seem implausible.