Because they were regarded as incompatible with principles of American law. (You will have to read further to find that out.)
The footnote that we discussed was not supported by reference to any case or Pennsylvania statute
No it was not. This is because "natural law" is not law according to statute, it is law according to nature. It would be contradictory to the concept of "natural law" to link natural law to a statute.
so it was probably a discussion of what the judges believed should be passed as a statute in Pennsylvania.
And where would they get an opinion so heavily contradictory to what the founders voted on in their own Capitol City of Philadelphia? I assure you, everyone in the legal community of Philadelphia knew what was the meaning and intent of "natural born citizen" during the convention in 1787.
It is very unlikely that anyone then present would get so terribly confused as to allow the Founders to go with English common law (which offers no protection from foreign intrigue) while all the Judges of the Supreme court of Pennsylvania, and several judges of the US Supreme court went with Vattel's principles of natural law.
How reasonable is it to believe there could be such a contradictory divide on this very relevant point at that time?
But, whatever it was, it was not binding on the Framers of our national Constitution.
More like it is the other way around. The legal system of Pennsylvania, which was by far the most exposed to the ideas of the convention, modeled itself after what those founders believed and told them.
It is more like the laws of Pennsylvania reflect the laws which the founders intended for the entire nation.
I have no doubt that Vattel had lots of fans, but I am also certain that he had plenty of critics.
He is the most cited Jurist during the first 50 years of this nation's history. (According to the Supreme court in the case of UNITED STATES STEEL CORPORATION et al., Appellants, v. MULTISTATE TAX COMMISSION )
Therefore I would suggest that his adherents far outnumbered his critics in American jurisprudence of the time period.
As I recall, he also believed it proper for a nation to prevent workers from emigrating to other countries if their labor was deemed to be important.
A policy which is currently followed by the United States of America right now. Nuke physicists and other critical technology experts are very heavily controlled on their travel to foreign countries. They have to get permission from the State Department in order to do so, if they are allowed to do so at all.
No, I have never seen that book, but if there is one thing of which I am certain, I am certain that where there existed support for a legal proposition in the form of a case or statute, the authors of that text would have utilized them. Along with that page from the text, you included the Act (statute) which requested that the court prepare the text. That Act reads in pertinent part as follows:
"That the Judges of the Supreme Court are hereby required to examine and report to the next Legislature, which of the English Statutes are in force in this Commonwealth, and which of those Statutes in their opinion ought to be incorporated into the Statute Laws of the Commonwealth."
In other words, the Legislature was requesting the Supreme Court to report to the Legislature about which English statutes were already duplicated by the statutes of Pennsylvania and which other English statutes the Supreme Court believed should be enacted by the state legislature. So, of course, the legislature wanted the Supreme Court to make reference to statutes existing in both England and Pennsylvania. I have not seen the entire text, but I am as certain as I can be that s Court wishing to describe the then existing laws of Pennsylvania would have made reference to any and all relevant statutes and case law. In fact, the very next paragraph cites a then existing federal statute. If you have a copy of that book, look around and I am certain that you will find many statutes and cases cited therein. Any competent effort to describe the current laws in any state will of necessity include references to relevant statutes and case law.
As to the definition of natural born citizen, it is not our fault that the authors of our Constitution did not provide a more detailed definition of the phrase. I suspect that every person at that Convention believed the matter to be of very little import compared to questions like the powers to be delegated to the three branches of the federal government, the relationship between the states and the federal government, how to protect little states from big states, etc. I doubt that you would have found anyone sitting in a corner worrying that Electors might have a difficult time interpreting this little phrase. Had they thought it more important, they would have said more than they did. No one should drive himself crazy over this relatively small matter. Use the definition that makes you most comfortable and all will be well.