"It was vital to the cause of the United States in that great struggle that they should be able to cut off the trade of the Southern States. The Confederate armies were dependent on supplies from overseas, and those supplies could not be obtained without exporting the cotton wherewith to pay for them.
"To cut off this trade the United States could only rely upon a blockade. The difficulties confronting the Federal Government were in part due to the fact that neighboring neutral territory afforded convenient centers from which contraband could be introduced into the territory of their enemies and from which blockade running could be facilitated.
"In order to meet this new difficulty the old principles relating to contraband and blockade were developed, and the doctrine of continuous voyage was applied and enforced, under which goods destined for the enemy territory were intercepted before they reached the neutral ports from which they were to be reexported. The difficulties which imposed upon the United States the necessity of reshaping some of the old rules are somewhat akin to those with which the Allies are now faced in dealing with the trade of their enemy."
Though an innovation, the extension of the British blockade to a surveillance of merchandise passing in and out of a neutral port contiguous to Germany was not for that reason impermissible. Thus that preceded the British contention, which, moreover, recognized the essential thing to be observed in changes of law and usages of war caused by new conditions was that such changes must "conform to the spirit and principles of the essence of the rules of war." The phrase was cited from the American protest by way of buttressing the argument to show that the United States itself, as evident from the excerpt quoted, had freely made innovations in the law of blockade within this restriction, but regardless of the views or interests of neutrals. These American innovations in blockade methods, Great Britain maintained, were of the same general character as those adopted by the allied powers, and Great Britain, as exemplified in the Springbok case, had assented to them. As to the American contention that there was a lack of written authority for the British innovations or extensions of the law of blockade, the absence of such pronouncements was deemed unessential. Sir Edward Grey considered that the function of writers on international law was to formulate existing principles and rules, not to invent or dictate alterations adapting them to altered circumstances.
So, to sum up, the modifications of the old rules of blockade adopted were viewed by Great Britain as in accordance with the general principles on which an acknowledged right of blockade was based. They were not only held to be justified by the exigencies of the case, but could be defended as consistent with those general principles which had been recognized by both governments.
The United States declined to accept the view that seizures and detentions of American ships and cargoes could justifiably be made by stretching the principles of international law to fit war conditions Great Britain confronted, and assailed the legality of the British tribunals which determined whether such seizures were prizes. Great Britain had been informed:
"... So far as the interests of American citizens are concerned the Government of the United States will insist upon their rights under the principles and rules of international law as hitherto established, governing neutral trade in time of war, without limitation or impairment by order in council or other municipal legislation by the British Government, and will not recognize the validity of prize-court proceedings taken under restraints imposed by British municipal law in derogation of the rights of American citizens under international law."
British prize-court proceedings had been fruitful of bitter grievances to the State Department from the American merchants affected. Sir Edward Grey pointed out that American interests had this remedy in challenging prize-court verdicts:
"It is open to any United States citizen whose claim is before the prize court to contend that any order in council which may affect his claim is inconsistent with the principles of international law, and is, therefore, not binding upon the court.
"If the prize court declines to accept his contentions, and if, after such a decision has been upheld on appeal by the judicial committee of His Majesty's Privy Council, the Government of the United States considers that there is serious ground for holding that the decision is incorrect and infringes the rights of their citizens, it is open to them to claim that it should be subjected to review by an international tribunal."