"To a man who has only a hammer, everything is a nail."
There are a panoply of arguments that fully answer the Vattelists.
Still, as they are intent on beating candidates such as Marco Rubio and Bobby Jindal, who are, under the jus soli approach to eligibility, fully eligible to be elected President, and they easily find the Vattelic stick. But that stick is not suited to the task, any more than a hammer is suited to the task of removing lug nuts, still, to those who have only a hammer (or Vattel's Law of Nations) everything is a nail (or a good time to invoke jus sanguinus).
It perplexes me. The invocation of Vattel does seem quite selective. Vattel wrote a treatise on the Law of Nations. In his treatise, he begins with the beginning of the topic of nations and he lays out in meticulous detail hundreds and hundreds legal considerations relevant to the creation and maintenance of States. Yet, out of all that Vattel writes of the Law of Nations, only jus sanguinus is invoked.
What do I mean?
Well, for example, in the Law of Nations, Vattel also discusses the wisdom of establishing public granaries. I'm including that section of his treatise below. He provides general principles of operation of such granaries that are, to say the least, inconsistent with the American preference for free market economies and individual choice in the use and disposition of one's property and labor:
§ 82. Of public granaries.
The establishment of public granaries is an excellent regulation for preventing scarcity. But great care should be taken to prevent their being managed with a mercantile spirit, and with views of profit. This would be establishing a monopoly, which would not be the less unlawful for its being carried on by the magistrate. These granaries should be filled in times of the greatest plenty, and take off the corn that would lie on the husbandman's hands, or be carried in too great quantities to foreign countries: they should be opened when corn is dear, and keep it at a reasonable price. If in a time of plenty they prevent that necessary commodity from easily falling to a very low price, this inconvenience is more than compensated by the relief they afford in times of dearth: or rather, it is no inconvenience at all; for, when corn is sold extremely cheap, the manufacturer, in order to obtain a preference, is tempted to undersell his neighbours, by offering his goods at a price which he is afterwards obliged to raise (and this produces great disorders in commerce, by putting it out of its course); or he accustoms himself to an easy life, which he cannot support in harder times. It would be of advantage to manufactures and to commerce to have the subsistence of workmen regularly kept at a moderate and nearly equal price. In short, public granaries keep in the state quantities of corn that would be sent abroad at too cheap a rate, and must be purchased again, and brought back at a very great expense after a bad harvest, which is a real loss to the nation. These establishments, however, do not hinder the corn trade. If the country, one year with another, produces more than is sufficient for the support of her inhabitants, the superfluity will still be sent abroad: but it will be sent at a higher and fairer price.Of course, Vattelists may wish to assert that the discussion of public granaries is merely an observation of the value to be found in the operation of such an enterprise, and is not a mandatory feature of the nation.
To which I will reply, "well, yes, precisely!" For it is in the nature of a treatise that it is a thorough and careful, complete discussion of a subject. In the case of Vattel's Law of Nations, his is a treatise that treats in detail and with care the broad topic captured in its title. But the law of nations is not, nor has it ever pretended to be THE LAW OF NATIONS. Instead, it is a thorough, expository, examination of its subject.
So, again, NO, we are not bound to Vattel. We are not bound to his preference for jus sanguinus over jus soli. Happily, we can be informed of a principle without having to conform to the principle, else we must begin to build the AmGranaries, the physical facilities of the National Granary Corporation.