The Power to Restrict Immigration and the Original Meaning of the Constitution's Define and Punish Clause

The Define and Punish Clause provides that “The Congress shall have Power . . . To define and punish Piracies and Felonies Committed on the High Seas, and Offenses against the Law of Nations.” ⁽²⁾ When the Constitution was written, “the law of nations” was the usual phrase for international law.

Because immigration is movement across national boundaries, the reference to “the Law of Nations” seems to invite consideration of whether the clause authorizes Congress to restrict immigration. Yet very few commentators have accepted that invitation. Those discussing the Define and Punish Clause almost invariably neglect to address immigration, ⁽³⁾ and those discussing immigration almost invariably overlook the Define and Punish Clause. ⁽⁴⁾

A few commentators have contended that the Constitution does not grant the federal government any authority over immigration at all—that the subject is one reserved to the states. ⁽⁵⁾ However, Article I, Section 9, Clause 1 of the Constitution seems inconsistent with that view. It provides:

The Migration or Importation of such Persons as any of the States now existing shall think proper to admit, shall not be prohibited by the Congress prior to the Year one thousand eight hundred and eight, but a Tax or duty may be imposed on such Importation, not exceeding ten dollars for each Person. ⁽⁶⁾

Although this provision usually is identified as a concession to the slave trade, the term “Migration” commonly was applied to free persons rather than slaves. ⁽⁷⁾ A free person migrating from France to New York State before 1808 was within the coverage of this clause: Congress could not prevent his immigration if New York State was willing to accept him. The necessary implication, however, is that beginning in 1808, Congress could prevent him from coming. ⁽⁸⁾ What specific constitutional provision granted Congress that authority?

Both the Supreme Court and commentators have cast about for an answer to that question. ⁽⁹⁾ In the 1875 case of Chy Lung v. Freeman, ⁽¹⁰⁾ the Court asserted that power to regulate immigration was latent in the Foreign Commerce Clause. ⁽¹¹⁾ This conclusion is open to the objection that mere non-commercial travel is not “commerce” as the Constitution uses the term. ⁽¹²⁾ In 1889, in Ping v. United States, the court shifted ground, relying instead on the doctrine of inherent sovereign authority. ⁽¹³⁾ That doctrine, however, contradicts the text of the Tenth Amendment. ⁽¹⁴⁾ Thus, as commentators have observed, the court's rulings seem “untethered to any constitutional power.” ⁽¹⁵⁾

Yet the Court's critics have done no better. ⁽¹⁶⁾ A few ⁽¹⁷⁾ have turned for guidance to the controversy over the Alien Act of 1798 ⁽¹⁸⁾ for insights on the source of the immigration power. That controversy does not provide much guidance, though, because it did not center on a law that restricted immigration; the Alien Act merely authorized the President to expel certain foreigners who had arrived legally. ⁽¹⁹⁾ Moreover, during the debate over the law, leading Founders were divided. ⁽²⁰⁾ Finally, because the controversy arose well after the Constitution was ratified, it tells us nothing about the ratifiers’ understanding of the document.

Most commentators do agree that the federal government's power to regulate immigration is implied rather than express, but this still begs the question of its ultimate source. On that issue, commentators divide: Some suggest “inherent sovereign authority,” ⁽²¹⁾ at least for purposes of criticism. ⁽²²⁾ Some suggest the “law of nations,” but in a manner unconnected to any specific constitutional grant. ⁽²³⁾ Others favor combinations of constitutional provisions such as the Naturalization ⁽²⁴⁾ and Foreign Commerce ⁽²⁵⁾ Clauses.

For the most part, therefore, the only thing the Supreme Court and most commentators agree on is, “The power's in there somewhere!” ⁽²⁶⁾ As often happens when writers fail to reconstruct the Constitution's original understanding, some blame the uncertainty on the framers’ bad drafting. ⁽²⁷⁾

In 2000, Christopher Blood, a law student, wrote about the then-famous case of Elian Gonzalez, a child captured in a federal raid and deported. ⁽²⁸⁾ Blood contended that the Define and Punish Clause was the source of the federal immigration power. However, he relied only on scanty evidence—most of it arising long before or long after the Constitution was adopted. ⁽²⁹⁾ His Founding-era evidence was not extensive. ⁽³⁰⁾

This article musters additional evidence and applies Founding-era interpretive methods ⁽³¹⁾ to it. The evidence shows that Christopher Blood was correct: The Define and Punish Clause is the fount of the congressional power to restrict immigration. Most of this additional evidence consists of standard works on the law of nations published before the thirteenth state, Rhode Island, ratified the Constitution on May 29, 1790. All these works were well-known and widely accepted in the United States. The evidence also includes two documents issued in 1791, but long in preparation and reflecting circumstances before 1791.

Whether Congress may “define” limits on immigration and “punish” infractions depends on whether the law of nations, as understood by the Constitution's ratifiers, encompassed immigration restrictions and whether a breach of those restrictions was seen as an “Offense” against the law of nations.

The migration rule of Article I, Section 9 demonstrates that Americans were conscious that restrictions on immigration might one day be imposed. However, that possibility provoked only slight notice during the ratification debates ⁽⁴⁵⁾—probably because the United States then had no such limits and, like other countries, sought security in higher populations. ⁽⁴⁶⁾ In other words, Americans thought they needed more immigrants, not fewer. ⁽⁴⁷⁾ This sentiment rendered immigration restrictions unlikely in the immediate future, so discussion centered on more pressing issues.

During the Founding era, American knowledge of the law of nations was shaped by treaties and treatises. Treaties commonly addressed the topic of cross-border migration, but usually emigration rather than immigration. ⁽⁴⁸⁾ However, treatises universally recognized as authoritative did discuss immigration.

One indication of whether the Founders considered a treatise authoritative is whether it appeared on a January 24, 1783 list of recommended books complied by a three-man committee of the Confederation Congress. The committee members were James Madison of Virginia, Hugh Williamson of North Carolina, and Thomas Mifflin of Pennsylvania—all three of whom were to serve among the Constitution's framers.

One section of the list was entitled “Law of Nature and Nations.” It included (1) several works on natural law, (2) several on aspects of the law of nations not related to immigration (such as the law of the sea and rules pertaining to ambassadors), and (3) five works devoted specifically to the law of nations. The committee report listed those five as— –

“Wolfius's Law of Nature;”

In addition, the committee recommended that Congress acquire a sixth work relevant to the law of nations: William Blackstone's Commentaries on the Laws of England. ⁽⁵⁰⁾ Blackstone's treatise was devoted mostly to the common law, but also contained an overview of international law. ⁽⁵¹⁾

Among these authors, the earliest in time was Hugo Grotius, who lived from 1583 to 1645. “Hugo Grotius” is a Latinized version of his Dutch name, Huig de Groot. Grotius was endowed with an astonishing intellect. That intellect, and his conscientious application, made him one of the leading figures of his age. ⁽⁵²⁾ In addition to law, his intellectual range included drama, philosophy, history, theology, and poetry—in Greek, Latin, and Dutch. Grotius also was a man of affairs and served in high office in the Netherlands. In 1618, however, he was caught in a political-religious dispute and illegally tried, convicted, and sentenced to life imprisonment. Two years later he escaped from his prison in a trunk, which, his wife assured the guards, contained only books and porcelain. ⁽⁵³⁾

The Netherlands never recalled Grotius from exile. He spent most of the remainder of his life in Paris. For many years he served the Swedish crown as its ambassador to France.

Grotius’ most important literary production was the three-volume set identified by the congressional committee as “Law of Nature and Nations.” It was published in 1625, initially in Latin, under the title, De Jure Belli ac Pacis. It established Grotius as the founder of modern international law. ⁽⁵⁴⁾

Despite the fact that Grotius’ treatise was over 150 years old when the Constitution was written, members of the founding generation still consulted it. Particularly popular was the edition translated and annotated by the French academic, Jean Barbeyrac (1674–1744). ⁽⁵⁵⁾

Chronologically, the next author on the congressional committee's list was the German scholar Samuel von Pufendorf (1632–1694). (Americans of the founding generation usually spelled his name “Puffendorf.”) Like Grotius, Pufendorf spent much of his life under the protection of the Swedish crown. ⁽⁵⁶⁾ He served as a professor at the University of Lund and, subsequently, as royal historiographer. He returned to Germany a year before his death and was awarded a barony. ⁽⁵⁷⁾

The congressional committee referred to Pufendorf's most famous work as “Law of Nature and Nations with notes by Barbeyrac.” Published in 1672, it was composed in Latin under the title De Jure Naturae et Gentium. A 1729 edition translated and annotated by Barbeyac became the standard. ⁽⁵⁸⁾

Chronologically, the next author on the committee's list was the German polymath Christian Wolff, who lived from 1679 to 1754. Wolff was a professor at the University of Halle. When forced to leave, he moved to the University of Marburg. Later he served as science adviser to Czar Peter the Great, and eventually returned in triumph to the University of Halle—as chancellor. ⁽⁵⁹⁾

In 1749, Wolff published in Latin the Jus gentium methodo scientifica pertractatum (“The law of nations treated thoroughly according to scientific method”). The author's surname was Latinized (awkwardly) into “Wolfius”—hence the congressional committee's designation of his book as “Wolfius's Law of Nature.”

Wolff was less known in America than Grotius or Pufendorf. ⁽⁶⁰⁾

Next on the list (again, in chronological order) was the book the committee described as “Burlamaque's Law of Nature and Nations.” Jean-Jacques Burlamaqui (1694–1748) was a natural law professor at the Academy of Geneva. He published his Principes du droit naturel in 1747. ⁽⁶¹⁾ In 1751, three years after his death, some of his academic colleagues supplemented his work by arranging his lecture notes into the Principes du droit politique.

“Vattel's Law of Nature and Nations,” as the congressional committee called it, originally was to be an elaboration on the Wolff's treatise, ⁽⁶²⁾ but it metamorphosed into something far more. Emir de Vattel (1714 to 1767) was a Swiss lawyer and diplomat who studied under Burlamaqui. ⁽⁶³⁾ Vattel served as a member of the privy council of the elector of Saxony and chief foreign affairs adviser to the Saxon government. ⁽⁶⁴⁾

Vattel published his work in French in 1758 under the title Le Droit des Gens. During the Founding-era, his was the most recent available work devoted exclusively to natural law and the law of nations and, at least among Americans, the most cited. ⁽⁶⁵⁾

Although not in the committee's list, one more international law scholar merits our attention. Georg Friedrich von Martens (1756–1821) was a professor at the University of Göttingen, in Germany. In 1789, Martens published Précis du droit des gens modernes de l’Europe. An English translation appeared six years later. ⁽⁶⁶⁾

Martens’ work was not available in time for the constitutional debates, but his period of composition was exactly contemporaneous with those debates. His treatise therefore reflects international law as it stood precisely when the Constitution was written and ratified. ⁽⁶⁷⁾

Today most Americans would be hard pressed to identify any legal scholar. This was not as true during the Founding era, due to the extraordinary legal literacy of the American population. Edmund Burke commented on it in his famous Speech on Conciliation with America, delivered in Parliament on March 22, 1775:

Permit me, Sir, to add another circumstance in our Colonies which contributes no mean part towards the growth and effect of this untractable spirit. I mean their education. In no country perhaps in the world is the law so general a study. The profession itself is numerous and powerful; and in most provinces it takes the lead. The greater number of the deputies sent to the [First Continental] Congress were lawyers. But all who read, and most do read, endeavor to obtain some smattering in that science. I have been told by an eminent bookseller, that in no branch of his business, after tracts of popular devotion, were so many books as those on the law exported to the Plantations. The Colonists have now fallen into the way of printing them for their own use. I hear that they have sold nearly as many of Blackstone's Commentaries in America as in England. General Gage marks out this disposition very particularly in a letter on your table. He states that all the people in his government are lawyers, or smatterers in law . . . . ⁽⁶⁸⁾

Understanding this legal literacy enables us to reconcile two statements about the Constitution that otherwise might seem contradictory: (1) It contained many legal terms of art ⁽⁶⁹⁾ and (2) it was designed to be understood (with some assistance from its sponsors) by the average, engaged eighteenth-century American.

William Blackstone (1723–1780), the author mentioned by Burke, was perhaps the most influential of all commentators on English law. He served as the first Vinerian Professor at Oxford University, as a Member of Parliament, and as a judge of the Court of Common Pleas. ⁽⁷⁰⁾ The four volumes of his Commentaries, which were based on his Oxford lectures, were published in English between 1765 and 1769.

As Burke suggested, Blackstone was enormously popular in the America. Citizens without direct access to the works of Grotius, Pufendorf, Barbeyrac, Wolff, Burlamaqui, or Vattel more likely had access to Blackstone. ⁽⁷¹⁾

During the eighteenth century, Grotius, Pufendorf, and Vattel all were regularly cited in and by American courts; ⁽⁷²⁾ Wolff less so. ⁽⁷³⁾ Contemporaneous citations to Blackstone are too numerous to list. ⁽⁷⁴⁾

Grotius's and Pufendorf's volumes were being sold in Philadelphia as early as the 1740s. ⁽⁷⁵⁾ Surveys of American eighteenth-century libraries show that books by several of our authors were common holdings. Pufendorf's work was tied for the tenth most common holding among law books in libraries in colonial (i.e., pre-1776) Virginia. ⁽⁷⁶⁾ A survey of the holdings in eighteenth century American libraries whose records are still extant (necessarily a limited set) identified no single law book owned by more than thirteen libraries. Blackstone's Commentaries was in ten, Vattel's Law of Nations in five, Grotius's De Juri Belli ac Pacis in three, and a shorter book by Grotius in five. ⁽⁷⁷⁾

Leading Founders relied freely on the authorities considered here. Thus, in the course of his 1774 essay defending the rights of the colonies against Great Britain, ⁽⁷⁸⁾ John Dickinson cited Grotius, Pufendorf, and Burlamaqui. ⁽⁷⁹⁾ John Adams’ Novanglus No. 6 cited Grotius, Pufendorf, and Barbeyrac. ⁽⁸⁰⁾ James Wilson's Collected Works include pre-ratification references to Burlamaqui. ⁽⁸¹⁾ At the Pennsylvania ratifying convention Wilson listed “Grotius and Puffendorf down to Vattel.” ⁽⁸²⁾ In his lectures on law, delivered shortly after the ratification, Wilson discussed all these authors at some length, including Wolff. ⁽⁸³⁾

References to these authorities also appear in the correspondence of John Adams, ⁽⁸⁴⁾ Abigail Adams, ⁽⁸⁵⁾ Alexander Hamilton, ⁽⁸⁶⁾ Thomas Jefferson, ⁽⁸⁷⁾ James Madison, ⁽⁸⁸⁾ John Francis Mercer, ⁽⁸⁹⁾ James Monroe, ⁽⁹⁰⁾ and Edmund Randolph. ⁽⁹¹⁾ These authorities also surfaced in the constitutional debates of 1787–90. Delegates to the Federal Convention cited Blackstone ⁽⁹²⁾ and Vattel. ⁽⁹³⁾ Participants in the subsequent ratification controversy, among them Alexander Hamilton, ⁽⁹⁴⁾ cited Blackstone extensively. ⁽⁹⁵⁾ Hamilton and Madison mentioned Grotius in Federalist Nos. 20 and 84, ⁽⁹⁶⁾ several other debate participants cited him, ⁽⁹⁷⁾ and a Rhode Island antifederalist wrote a public letter over the name of the great Hollander. ⁽⁹⁸⁾

Other participants in the ratification debates referenced Pufendorf ⁽⁹⁹⁾ and, much more often, Vattel. ⁽¹⁰⁰⁾ Some listed several of these scholars in one place—as when the Federalist author writing under the pseudonym “Margery” commended “a Constitution, which is the combined result of all the wisdom of Grotius, Puffendorf, Barbeyrac, and Burlamaqui.” ⁽¹⁰¹⁾

Several of these scholars also made their appearance in the state ratifying conventions and associated proceedings. As noted above, James Wilson cited Grotius, Pufendorf, and Vattel at the Pennsylvania convention. ⁽¹⁰²⁾ At the Virginia convention, William Grayson, an antifederalist, asked, “If nine states give [navigation rights to the Mississippi] away, what will the Kentucky people do? Will Grotius and Puffendorf relieve them?” ⁽¹⁰³⁾ During the South Carolina legislative session leading to a convention in that state, Charles Cotesworth Pinkney cited Burlamaqui ⁽¹⁰⁴⁾ and he and Rawlins Lowndes debated comments by Vattel. ⁽¹⁰⁵⁾

We can say with confidence, therefore, that the Founders considered these writers on the law of nations to be reasonably authoritative.

Pufendorf, Barbeyac, Vattel, Martens, Blackstone, and—more obliquely, Grotius and Burlamaqui—all addressed limits on immigration when writing on the law of nations. These authors consistently recognized the prerogative of governments to impose immigration restrictions. That prerogative was qualified in cases of necessity (for example, a ship being driven by storm onto a foreign shore), and in the cases of exiles and fugitives. As to voluntary immigrants, however, all but Grotius—the earliest of the writers—recognized that the power to restrict was nearly absolute. Grotius made an exception for foreigners who wished to settle on barren lands. Later writers rejected that exception.

The remainder of this Part summarizes in more detail the positions of these seven authors.

Hugo Grotius treated the issue of trans-border migration within his wider discussion of the law of nations. On the then-controversial subject of emigration, he wrote that the legal default position was that a person had a right to leave his homeland. However, he added, “[O]ne is not to go out of the State, if the Interest of the Society requires that he should stay in it.” ⁽¹⁰⁶⁾ The effect of that statement was to validate restrictions based on the sovereign's view of the interests of society.

In his discussion of immigration, Grotius did not set forth a default position explicitly, but assumed that, absent special circumstances, a person may not immigrate to a foreign nation without permission from the sovereign of that nation. Thus, he wrote, “To receive particular Persons as are willing to remove from one Prince's Territories into another's, is no Breach of Friendship; for this Liberty is not only natural, but has something favourable in it (as we have said elsewhere).” ⁽¹⁰⁷⁾ Of course, if states were required to admit foreigners, the statement would be unnecessary because complying with a mandatory rule could not be a “Breach of Friendship.”

Grotius did offer several qualified exceptions to the rule that immigration requires the permission of the receiving country. One exception applied to those who seek only a short sojourn “on account of their Health, or for any other just Cause.” ⁽¹⁰⁸⁾ Such people could even erect a temporary shelter in which to stay. ⁽¹⁰⁹⁾ Another exception applied to exiles, because “a fixed Abode ought not to be refused to Strangers, who being expelled from their own Country, seek a Retreat elsewhere.” ⁽¹¹⁰⁾ His most controversial exception was as follows:

And if there be any waste or barren Land within our Dominions, that also is to be given to Strangers, at their Request, or may be lawfully possessed by them, because whatever remains uncultivated, is not to be esteemed a Property, only so far as concerned Jurisdiction, which always continues the Right of the antient People. ⁽¹¹¹⁾

As we shall see, none of the later authorities agreed with Grotius on that point.

One modern commentator claims that, “Samuel Pufendorf . . . denied to the sovereign a right to exclude aliens, so long as they had lawful reasons, including economic ones, for seeking admission into states.” ⁽¹¹²⁾ Another classifies Pufendorf's views on the power to restrict immigration as “ambiguous.” ⁽¹¹³⁾

Nothing could be further than the truth. Although Pufendorf commended the virtue of hospitality, he made it clear that in cases other than fugitives or exiles, whether a foreigner could immigrate was subject to the decision of the receiving nation. Speaking of travelers, Pufendorf wrote:

The Case is somewhat like that of a private Man, who in his House or Gardens, possesses some rare Curiosity, or other valuable Sight; such an one does not apprehend himself tied freely to let in all Spectators; but whoever is thus gratified either rewards, or at least acknowledges, it as an extraordinary Favour. ⁽¹¹⁴⁾

He then expanded the point to include permanent immigration as well as travel:

And farther, it seems very gross and absurd, to allow others an indefinite Right of travelling and living amongst us, without reflecting either on their Number, or on the Design of their coming; whether supposing them to pass harmlessly, they intend only to take a short view of our Country, or whether they claim a Right of fixing themselves with us forever. And that he who will stretch the Duty of Hospitality to this extravagant Extent, ought to be rejected as a most unreasonable, and most improper judge of the Case.

* * * *

As to our main Question, it is look’d on by most as the safest way of resolving it, to say, That it is left in the power of all States, to take such Measures about the Admission of Strangers, as they think convenient; those being ever excepted, who are driven on the Coasts by Necessity, or by any Cause that deserves Pity and Compassion. ⁽¹¹⁵⁾

Even in the cases of refugees and exiles, there were limits to hospitality:

Humanity, it is true, engages us to receive a small number of Men expell’d their Home, not for their own Demerit and Crime . . . But no one will be fond of asserting, that we ought in some manner to receive and incorporate a great Multitude . . . Therefore every State may be more free or more cautious in granting these Indulgences, as it shall judge proper for its Interest and Safety. ⁽¹¹⁶⁾

Pufendorf enumerated factors a state should consider in weighing whether to accept exiles and fugitives. Among these were the fertility of the country, the density of the existing population, whether the prospective newcomers were “industrious, or idle,” and whether they could be located so as to “render them incapable of giving any Jealousy to the Government.” ⁽¹¹⁷⁾

Pufendorf's position was clear: A state should consider both interest and the duties of humanity, but exactly where it drew the line was a matter for its own discretion. There is no indication that he accepted Grotius’ view that a state was obligated to accept immigrants willing to settle on unused ground.

Jean Barbeyrac's annotations of Pufendorf's immigration coverage revealed no objection to that author's positions. But Barbeyrac's annotations of Grotius's work sharply criticized Grotius's claim that a state must allow immigrants to settle on vacant land:

I am not of our Author's Opinion on this Point; nor can I think the Reason here alledged [sic]solid. All the Land within the Compass of each respective Country is really occupied; tho’ every Part of it is not cultivated, or assigned to anyone in particular: It all belongs to the Body of the People. The Author here reasons on a false Idea of the Nature of taking Possession . . . The Inundations of so many barbarous People, who under Pretense of seeking a Settlement in uncultivated Countries, have driven out the native Inhabitants, or seized on the Government, are a good Proof of what I advance. See Pufendorf, B. III. Chap. III, § 10. ⁽¹¹⁸⁾

Another commentator on Grotius also dissented from the master on this point. In 1707, the University of Edinburgh, Scotland published a “Compendium” (literally, “short cut”—an abridgement) of Grotius's De Jure Belli ac Pacis for student use. ⁽¹¹⁹⁾ The Compendium, which was published in Latin, consisted of successive extracts from Grotius's work, followed by unsigned commentary on each extract. The commentary on Grotius's view that foreigners have a right to settle in vacant territory generally follows Barbeyrac's position:

However, to receive any and all migrants into the state is not only dangerous, but is not a position appropriate for any state; for the purpose of the state is the happiness of its citizens, which is obstructed by the indiscriminate receiving of all and the introduction of foreign customs. In this respect mercy must be tempered, lest we ourselves become objects of mercy to others. And it should be properly considered whether the productiveness of our soil is such as can support them comfortably, whether they are a skillful or lazy group of people who should be admitted, whether the newcomers can be so distributed and located so that they pose no threat to the state.

If, moreover, some place is given by us to them for settlement, then it should be accounted an accommodation to them; from which it follows that they can’t take any location they please or that they can occupy any place that happens to be vacant as if it were a matter of right—since no place within our territory can be reckoned without ownership by either private or universal public occupation. Therefore, whatever uncultivated and deserted land is found within the kingdom, then the decision of the authorities awards it to a person who desires it so that it is acquired by the possessors not by occupation but by assignment. ⁽¹²⁰⁾

Again, the message is clear: As a matter of the law of nations, the extent to which a state must admit immigrants is for that state to decide.

Christian Wolff also has been the victim of distortion by a modern commentator, who claims Wolff adopted “a principle of free movement, subject to several stipulated exceptions within the discretion of states . . . Wolff was instrumental in taking account of political realities by according limited regulatory powers to the sovereign to protect morals, religion, public safety, and public welfare, while maintaining the principle of free migration.” ⁽¹²¹⁾

Wolff's text tells a different story. ⁽¹²²⁾ It emphasized that “No people, nor any private traveler, can appropriate to himself anything in foreign territory,” ⁽¹²³⁾ for the territory is subject to the nation or ruler thereof. ⁽¹²⁴⁾ Because no traveler could appropriate any right in foreign territory, one was not permitted to violate the sovereign's barrier to entry. This was true whether the person sought to enter for no reason or for a special business, “insofar as the prohibition extends.” ⁽¹²⁵⁾ Moreover, to ensure that a prohibition on entry had practical effect, the sovereign could devise penalties for disobedience. ⁽¹²⁶⁾

Like other writers, Wolff was somewhat more forgiving toward exiles. But even as to exiles he permitted denial of residence if there was good reason. ⁽¹²⁷⁾ Good reasons included, among other factors, the convenience of the people, living space, prejudice to religion or culture, and the risk of admitting criminals. ⁽¹²⁸⁾

Ultimately, Wolfe's view was that access to a foreign country depended entirely on the will of that country's sovereign. ⁽¹²⁹⁾

Jean-Jacques Burlamaqui's work was more about natural and domestic law than about the law of nations, and his treatment of immigration was more oblique than the treatment by most of our other authors. In keeping with the spirit of the times, Burlamaqui believed that immigration should be encouraged:

First then it is evident, that the force of a state, with respect to war, consists chiefly in the number of its inhabitants; sovereigns therefore ought to neglect nothing than can either support or augment the number of them.

Among the other means, which may be used for this purpose, there are three of great efficacy. The first is, easily to receive all strangers of a good character, who want to settle among us . . . . ⁽¹³⁰⁾

Yet, an inference from this statement is that a sovereign could withhold permission to immigrate. The same inference follows from several other statements: –

a sovereign may prohibit the importation of foreign commodities; ⁽¹³¹⁾

Some confirmation comes from Burlamaqui's statements on emigration. Although Burlamaqui wrote that the right to emigrate “is a right inherent in all free people,” ⁽¹³⁴⁾ in fact, he sharply qualified it in several ways. He concluded that “If the laws of the country have determined any thing in this point, we must be determined by them; for we have consented to those laws in becoming members of the state. ⁽¹³⁵⁾

When the Constitution was written, Emer de Vattel's treatise was the most recently-published international law book freely available, and probably the most influential. For that reason—and because some modern commentators have suggested that Vattel's work does not support the power of a sovereign to restrict immigration ⁽¹³⁶⁾—we will examine his treatment of the subject in some detail.

Vattel's work comprised four books. Book I was entitled “Of Nations considered in themselves.” A major theme of Book I was the derivation of rules of governance from natural law principles. Among his conclusions: –

“A nation or state has a right to every thing that can help to ward off imminent danger;” ⁽¹³⁷⁾

Vattel's belief that a state may restrict immigration influenced his definition of “inhabitants.” That term included both citizens and “foreigners, who are permitted to settle and stay in the country.” ⁽¹⁴³⁾

One might object that the title of Book I—“Of Nations considered in themselves”—suggests that it was devoted only to domestic, intra-state law. If so, one might contend, the immigration restrictions listed in Book I could be mere municipal regulations rather than part of the law of nations.

It is true that much of Book I addressed purely domestic questions, such as how legislation is adopted, how a sovereign should relate to its subjects, and rules of private and state property. Yet it also addressed transborder issues of the kind arising among sovereignties—that is, issues within the realm of international law. One usually can tell from the context whether the author was discussing an issue of municipal or international law. ⁽¹⁴⁴⁾ Still, discussion of immigration restrictions in Book I does not prove that Vattel considered those restrictions to be matters of international law or that violations of those restrictions were “Offenses against the Law of Nations.”

Book II was entitled “Of a Nation Considered in its Relation to Others,” and was, in fact, devoted wholly to the law of nations. (The third and fourth books were about war and peace, respectively.) Book II leaves no doubt that immigration was a “law of nations” issue. Here is part of Book II's treatment of immigration:

The sovereign may forbid the entrance of his territory either to foreigners in general, or in particular cases, or to certain persons, or for certain particular purposes, according as he may think it advantageous to the state. There is nothing in all this, that does not flow from the rights of domain and sovereignty: every one is obliged to pay respect to the prohibition; and whoever dares to violate it, incurs the penalty decreed to render it effectual. ⁽¹⁴⁵⁾

Vattel added that “the least encroachment on the territory of another is an act of injustice . . .” ⁽¹⁴⁶⁾ Like other writers, he rejected Grotius's view that a sovereign must suffer immigrants to enter deserted territories under the control of the sovereign:

As every thing included in the country belongs to the nation,—and as none but the nation, or the person on whom she has devolved her right, is authorised to dispose of those things . . . ,— if she has left uncultivated and desert places in the country, no person whatever has a right to take possession of them without her consent. Though she does not make actual use of them, those places still belong to her: she has an interest in preserving them for future use, and is not accountable to any person for the manner in which she makes use of her property. ⁽¹⁴⁷⁾

The categorical right to exclude also implied the right to admit under conditions:

Since the lord of the territory may, whenever he thinks proper, forbid its being entered . . . , he has no doubt a power to annex what conditions he pleases to the permission to enter. This, as we have already said, is a consequence of the right of domain. ⁽¹⁴⁸⁾

The law of nations also encompassed an individual duty to obey: “We should not only refrain from usurping the territory of others; we should also respect it, and abstain from every act contrary to the rights of the sovereign;” ⁽¹⁴⁹⁾ and “[E]very one is obliged to pay respect to the prohibition; and whoever dares to violate it, incurs the penalty decreed to render it effectual.” ⁽¹⁵⁰⁾

Apparently, in Vattel's view, a sovereign that does not restrain its inhabitants from breaching another country's immigration laws also violates the law of nations: “If a sovereign, who might keep his subjects within the rules of justice and peace, suffers them to injure a foreign nation either in its body or its members, he does no less injury to that nation, than if he injured it himself.” ⁽¹⁵¹⁾ Or, more specifically: “[T]here is another case where the nation in general is guilty of the crimes of its members. That is when by its manners and by the maxims of its government it accustoms and authorizes its citizens to plunder and maltreat foreigners, to make inroads into neighboring countries, &c.” ⁽¹⁵²⁾

Like other international law writers familiar to the Founders, Vattel believed a sovereign had some obligation to consider admitting exiles and fugitives. However, those making the decision had to weigh the consequences, and could either deny refuge altogether or place conditions on it. ⁽¹⁵³⁾

Georg Friedrich von Martens was forthright on the power of a sovereign to exclude foreigners:

From the moment a nation have taken possession of a territory in right of first occupier, and with the design to establish themselves there for the future, they become the absolute and sole proprietors of it, and all that it contains; and have a right to exclude all other nations from it, to use it, and dispose of it as they think proper . . . . ⁽¹⁵⁴⁾

Martens deduced several conclusions from this general proposition. One was that because foreigners could be excluded entirely, they also could be admitted on condition. Speaking of taxation, Martens wrote, “A foreigner enjoying the protection of the state, cannot, while he remains in it, expect to be entirely exempted from imposts. Besides, it may be made a condition of his admission . . . .” ⁽¹⁵⁵⁾ For the same reason, a sovereign could admit foreigners on the condition that they sacrifice their inheritance to the state:

From the right of excluding all foreigners from the territory is derived another right, the Droit d’Aubaine. In virtue of this right, the heritage [i.e., inheritance] of a foreigner, who dies without leaving heirs in the country, falls to the sovereign, or to the chief magistrate of the place where he dies, to the exclusion of the heirs that he may have out of the country. ⁽¹⁵⁶⁾

The fact that Martens included this material in a book on the “law of nations” precisely when the Constitution was being composed and debated strengthens the inference that the contemporaneous meaning of the “law of nations” included power to control, or even prohibit, immigration.

William Blackstone's work dealt principally with the common law of England, but he also outlined some general rules from the law of nations. One was that, with minor qualifications, a state had the right to exclude foreigners:

Upon exactly the same reason stands the prerogative of granting safe-conducts, without which by the law of nations no member of one society has a right to intrude into another. And therefore Puffendorf very justly resolves, that it is left in the power of all states, to take such measures about the admissions of strangers, as they think convenient; those being ever excepted who are driven on the coasts by necessity, or by any cause that deserves pity or compassion. ⁽¹⁵⁷⁾

Clearly, Blackstone believed that the sovereign's prerogative to exclude was very extensive.