As Andy notes below, President Trump has again raised the issue of birthright citizenship, this time suggesting he could end it by executive order.
In the summer issue of National Affairs, two distinguished scholars of the Constitution (one of whom, Rogers Smith, is also the president of the American Political Science Association this year) took up the matter, and came to the same conclusion Andy does: The Constitution does not decisively resolve the question, and actually leaves it open to Congress, but not to the president acting on his own. “Birthright citizenship,” they write, “is a legitimate political and policy question, and a hard one.” But that does not make it a question open to resolution by executive action.