In systems based on the common law, like the one in US, judges can pretty much decide anything. It’s typical in US now for the Supreme Court to just say “we now interpret the constitution in a different way” and invent some completely new laws (like they did twice with abortion). So the constitution says that people born in US are citizens and the Supreme Court will say “we now decide it doesn’t really mean that, people born in US are not automatically citizens” and then the government will change the laws accordingly. So I imagine they will say that only being born to citizens parents grants you citizenship and everyone born to parents without citizenship will lose their citizenship. The government will then decide what to do with all those people. They can for example declare that anyone born in US before 1900 still is considered citizen and it applies to all their descendants. Anyone born after 1900 who came from European countries automatically gets citizenship but people that immigrated from south America or Africa don’t.
In systems based on the common law, like the one in US, judges can pretty much decide anything. It’s typical in US now for the Supreme Court to just say “we now interpret the constitution in a different way” and invent some completely new laws (like they did twice with abortion). So the constitution says that people born in US are citizens and the Supreme Court will say “we now decide it doesn’t really mean that, people born in US are not automatically citizens” and then the government will change the laws accordingly. So I imagine they will say that only being born to citizens parents grants you citizenship and everyone born to parents without citizenship will lose their citizenship. The government will then decide what to do with all those people. They can for example declare that anyone born in US before 1900 still is considered citizen and it applies to all their descendants. Anyone born after 1900 who came from European countries automatically gets citizenship but people that immigrated from south America or Africa don’t.