PS:
Es ist aus meiner Sicht kein nationalstaatliches Grundprinzip, da es auf die ursprünge der Demokratie in den griechischen Stadtstaaten zurückgeht:
"Metoikos (literally ‘household-changer’), our ‘metic’, was the category into which any non-Athenian wanting residence in Athens was placed. While having no citizen rights, of which Athenians were very jealous, they did have access to the courts; but they were...
https://www.spectator.co.uk/article/how-ancient-athens-handled-immigrants/