I, too, would like to see the codified book of Natural Law that keeps getting cited.
And being a born citizen is what law and logic affirm as natural born....as well as the naturalization law of 1793.
Ummmm, perhaps you've never read the Declaration of Independence?
When in the Course of human events, it becomes necessary for one people to dissolve the political bands which have connected them with another, and to assume among the powers of the earth, the separate and equal station to which the Laws of Nature and of Nature's God entitle them, a decent respect to the opinions of mankind requires that they should declare the causes which impel them to the separation.
Just words, I'm sure they didn't really men that when it is convenient to do so....
Blackstone would come pretty close to describing natural law (and the Declaration of Independence, too); but neither Blackstone nor the DoI were or are in any way binding law. They are historical curios.