At least since as early as June 5, 1793, in the letter of Mr. Jefferson, Secretary of State, to the French Minister, our Government has recognized the law of nations as an "integral part" of the laws of the land.
To ascertain international law, "resort must be had to the customs and usages of civilized nations; and, as evidence of these, to the works of commentators and jurists. * * * Such works are resorted to by judicial tribunals * * * for trustworthy evidence of what the law really is."
Let us first see the position of our Government, and then ascertain whether that position has authoritative support. Mr. Lansing, in his official communication to the German Government dated June 9, 1915, stated:
Mr. Lansing's communication.
Responsibility of the German Government.
A principle of humanity.
"But the sinking of passenger ships involves principles of humanity which throw into the background any special circumstances of detail that may be thought to affect the cases, principles which lift it, as the Imperial German Government will no doubt be quick to recognize and acknowledge, out of the class of ordinary subjects of diplomatic discussion or of international controversy. Whatever be the other facts regarding the Lusitania, the principal fact is that a great steamer, primarily and chiefly a conveyance for passengers, and carrying more than a thousand souls who had no part or lot in the conduct of the war, was torpedoed and sunk without so much as a challenge or a warning, and that men, women, and children were sent to their death in circumstances unparalleled in modern warfare. The fact that more than one hundred American citizens were among those who perished made it the duty of the Government of the United States to speak of these things and once more with solemn emphasis to call the attention of the Imperial German Government to the grave responsibility which the Government of the United States conceives that it has incurred in this tragic occurrence, and to the indisputable principle upon which that responsibility rests. The Government of the United States is contending for something much greater than mere rights of property or privileges of commerce. It is contending for nothing less high and sacred than the rights of humanity, which every Government honors itself in respecting and which no Government is justified in resigning on behalf of those under its care and authority. Only her actual resistance to capture or refusal to stop when ordered to do so for the purpose of visit could have afforded the commander of the submarine any justification for so much as putting the lives of those on board the ship in jeopardy. This principle the Government of the United States understands the explicit instructions issued on August 3, 1914, by the Imperial German Admiralty to its commanders at sea to have recognized and embodied as do the naval codes of all other nations, and upon it every traveler and seaman had a right to depend. It is upon this principle of humanity, as well as upon the law founded upon this principle, that the United States must stand. * * *
Americans must be safeguarded.
"The Government of the United States cannot admit that the proclamation of a war zone from which neutral ships have been warned to keep away may be made to operate as in any degree an abbreviation of the rights either of American shipmasters or of American citizens bound on lawful errands as passengers on merchant ships of belligerent nationality. It does not understand the Imperial German Government to question those rights. It understands it, also, to accept as established beyond question the principle that the lives of non-combatants cannot lawfully or rightfully be put in jeopardy by the capture or destruction of an unresisting merchantman, and to recognize the obligation to take sufficient precaution to ascertain whether a suspected merchantman is in fact of belligerent nationality or is in fact carrying contraband of war under a neutral flag. The Government of the United States therefore deems it reasonable to expect that the Imperial German Government will adopt the measures necessary to put these principles into practice in respect of the safeguarding of American lives and American ships, and asks for assurances that this will be done. (See White Book of Department of State entitled 'Diplomatic Correspondence with Belligerent Governments Relating to Neutral Rights and Duties, European War, No. 2,' at p. 172. Printed and distributed October 21, 1915.)"
The German Government found itself compelled ultimately to recognize the principles insisted upon by the Government of the United States, for, after considerable correspondence, and on May 4, 1916, (after the Sussex had been sunk,) the German Government stated: