at the time of the adoption of that instrument." Thompson v. Utah 

 (1898), 170 U. S. 343. 



The law of nations was not something newly created by this 

 clause of the Constitution; it is recognized as existent, to determine 

 whose nature and extent resort must be had to English jurispru- 

 dence. 



The English cases previously cited and the paragraph quoted 

 from Blackstone show, it is believed, that international law was a 

 part of the common law. As, therefore, the lawyers who framed 

 the provisions of the Constitution were trained in the common law, 

 and were familiar with its principles from a careful study of the 

 Commentaries, it is impossible to consider the law of nations other 

 than as a part of the common law of England, and by the Constitu- 

 tion of the United States it is, therefore, a fundamental and integral 

 part of our jurisprudence. 



But there is another not less potent argument for this view. 

 Congress is given power to punish offenses against the law of na- 

 tions. The law of nations is thus contemplated as an existing 

 system and part of our municipal law. Else why is Congress given 

 power to punish the violation? For it is elementary that nations 

 do not, as a rule, punish breaches of foreign law. Infractions of 

 the municipal code are a sufficient tax for judge and legislature^ 

 It is likewise elementary that Congress may indeed vary the law of 

 nations in so far as our citizens are concerned, and that the courts 

 would be compelled to give effect to the statute; but it is equally 

 clear that the Act of Congress in such cases would be construed 

 with evident reluctance and great strictness. 



Even before the formation of the present Constitution, the 

 Federal Court of Appeals admitted, in a single and well-chosen 

 phrase, the superiority of international over municipal law: "The 

 municipal laws of a country cannot change the law of nations so 

 as to bind the subjects of another nation." (The Resolution, 1781, 

 2 Dallas, 1, 4.) But, if nations may not alter international law, 

 they may, by their municipal law, according to Chief Justice 

 M'Kean, in the case of Ross v. Rittenhouse (1792), 2 Dallas, 160, 162, 

 "facilitate or improve the execution of its decisions, by any means 

 they shall think best, provided the great universal law remains 

 unaltered." 



If that be the measure of municipal power, it follows that any 

 attempt to enlarge the boundaries of municipal at the expense of 

 international law will be regarded with suspicion. Thus, in the 

 case of The Charming Betsy (1804), 2 Cr. 64, 118, Mr. Chief Justice 

 Marshall said: " It has also been observed that an Act of Con- 

 gress ought never to be construed to violate the law of nations 

 if any other possible construction remains, and consequently can 



