Claim of the United States for amount of moneys expended in the investigation, preparationand proof of its case denied as they were in the nature of expenses of the presentation of thecase, which, according to the Arbitration Convention, are to be paid by each government;nor are such costs claimable under the heading of damages. When a state espouses a private claim on behalf of one o f its nationals, expenses whichthe latter may have incurred in establishing orprosecuting his claim prior to espousal by thegovernment may, under appropriate conditions,be legitimately included in the claim, but the Tribunal knew of no case in which a government has sought or been allowed indemnity for expenses incurred in preparing the proof or presenting a national or private claim before an international tribunal.

In the absence of international cases on the subject, there are certain decisions of the Supreme Court of the United States dealing with both air pollution and water pollution which may legitimately be taken as a guide in this field of international law where no contrary rule prevails in international law ana no reason for rejecting such precedents can be induced from the limitation of sovereignty inherent in the Constitution o f the United States.

The Tribunal finds that under the principles of international law, as well as the law of the United States, no state has the right to use or permit the use of its territory in such a manner as to cause injury by fumes in or to the territory of another or the properties or persons therein,'whe the case is of serious consequence and theinjury is established by clear and convincing evidence.

The Tribunal therefore holds that the Dominion o f Canada is responsible in international law for the conductofthe Trail Smelter and that it is the duty o f the Government of the Dominion of Canada to see to it that this conduct is in conformity with the obligation of the Dominion under international law as herein determined.

No damage has occurred since the previous award o f the Tribunal (this JUURNAL, Vol. 33,1939, p. 182).

The Trail Smelter shall be required to refrain in the future from causing any damage through fumes in the State of Washington. To avoid such damage the operations of the Smelter shall be subject to a regime or measure of control as provided in the present decision. Should such damage occur, indemnity to the United States shall be fixed in such manner as the Governments acting under the convention may agree upon.