https://www.supremecourt.gov/opinions/24pdf/24a884_8n59.pdf Justice Sotomayor dissents: > Instead, the Government says, it should be able to apply the Citizenship Order (whose legality it does not defend) to everyone except the plaintiffs who filed this lawsuit. If that’s the case, I’m curious if it could be fixed with a class action, so everyone (or everyone born in the US) is a plaintiff? If that’s legally a thing.
It could be fixed for the class with a class action. But the courts have also don't their damndest to make that hard too. Requiring a class action means that courts have the additional opportunity to say "nope that's not a valid class" (WalMart v Dukes being a rather famous example).
I read the Wikipedia article [0] and I would point out that a class defined by birth place would pass easily Scalia's test for commonality. So it seems that using a class action suit that includes every person born in US of un-documented parents would work. (But who knows what other tests the Supreme Court would come up now...)
[0] - https://en.wikipedia.org/wiki/Wal-Mart_Stores,_Inc._v._Dukes