But we'll just have to watch cases like https://thewire.in/caste/cisco-case-caste-discrimination-sil... to see whether the courts agree with us that caste discrimination should be illegal in America. (And if the courts disagree, time to lobby the politicians...)
https://www.americananthro.org/ConnectWithAAA/Content.aspx?I...
The postmodern term is "ethnicity" (which does get mentioned in your article), with the understanding that it's overwhelmingly about culture, and while genetics do matter in very specific cases (like for lactose tolerance), typically they matter very little, and your ethnicity is something that you can change (though it gets ever harder after your teenage years).
P.S.: I really don't know enough about "caste" and its history to comment on that, though the ancestry issue doesn't look good.
(One thing that has been bugging me for a while is how the number of our ancestors grows exponentially with each generation - at least before inbreeding starts to dominate - which seems like any of those ancestry-based discriminations are just arbitrarily stopping at some convenient for them point/in complete coverage, and can basically make up excuses about discriminating against you or not. But I guess that I shouldn't be surprised about it when totalitarian regimes do it : the fear of the arbitrary is a powerful weapon they have, and so it's likely on purpose !)
How? Dalits aren't from Dalitland.
It'll come down to a judge, but it doesn't seem like a stretch to put a caste group under that umbrella.
[0] https://www.justice.gov/crt/federal-protections-against-nati...
Basically because it wasn't on the radar of American legislators when they wrote up the lists of protected classes.
