[Non-Sequitur]

Restated: It sure the hell sounds like Justice Gray believes "common-law" is Vattel.

Except that quote is from Justice Fuller's dissenting opinion and not the majority opinion written by Justice Gray. And as I assume you know, dissenting opinions are not binding, do not form precedent, and are not part of case law.

Link

[BP2]

Justice Gray mirrors Justice Fuller's dissenting Opinion citation, about 11 paragraphs down in the ruling Opinion:

The Constitution nowhere defines the meaning of these words, either by way of inclusion or of exclusion, except insofar as this is done by the affirmative declaration that “all persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States.” In this as in other respects, it must be interpreted in the light of the common law, the principles and history of which were familiarly known to the framers of the Constitution. Minor v. Happersett, 21 Wall. 162; Ex parte Wilson, 114 U.S. 417, 422; Boyd v. United States, 116 U.S. 616, 624, 625; Smith v. Alabama, 124 U.S. 465. The language of the Constitution, as has been well said, could not be understood without reference to the common law. Kent Com. 336; Bradley, J., in Moore v. United States, 91 U.S. 270, 274. [p655]

In Minor v. Happersett, Chief Justice Waite, when construing, in behalf of the court, the very provision of the Fourteenth Amendment now in question, said: “The Constitution does not, in words, say who shall be natural-born citizens. Resort must be had elsewhere to ascertain that.”

Furthermore, if anyone is going to erroneously re-construct Blackstone's definition of "Natural Born Subject" into "Natural Born CITIZEN" — in 1787, 1898 or 2010 — they CANNOT ignore this section from Blackstone Commentaries — which DIRECTLY pertains to Obama's status being born a British Subject:

Its an ALL or NOTHING deal, Non-Seq.