I'm looking forward to the first Twitter controversies about who does or doesn't qualify as black, when someone judged too white (or Indian or Syrian or South-American) manages to get the "black-identifying" label and gets caught.
There is some precedent that is related. A certain percentage of DOD contracts are required to go to Native American owned business. To qualify as native the business must be 51% owned by member(s) of a federally recognized tribe. Each tribe gets to decide who is or is not a member, most do it by voting or birthright systems.
Interestingly, for some other set asides they use "Historically black colleges and universities (HBCUs)" as the qualifier. Membership is regulated by who gets in to those colleges. Thus they use college admissions boards instead of birthright or popular vote.
Yeah, this and international differences about what "black" actually means. By standards of some cultures Barack Obama was not the first black president of the US but the first mulatto president of the US, as he is neither "properly" black nor white.
If we used that standard, then almost no African American in existence would be considered Black. Since effectively all Black people with enslaved ancestors in America have some white ancestry.
