The Matter and the Party are the first Conditions of the federal Jurisdiction.--Suits in which Ambassadors are engaged.--Suits of the Union.--Of a separate State.--By whom tried.--Causes resulting from the Laws of the Union.--Why judged by the federal Tribunal.--Causes relating to the Non-performance of Contracts tried by the federal Courts.--Consequences of this Arrangement. After having appointed the means of fixing the competency of the federal courts, the legislators of the Union defined the cases which should come within their jurisdiction. It was established, on the one hand, that certain parties must always be brought before the federal courts, without any regard to the special nature of the cause; and, on the other, that certain causes must always be brought before the same courts, without any regard to the quality of the parties in the suit. These distinctions were therefore admitted to be the bases of the federal jurisdiction. Ambassadors are the representatives of nations in a state of amity with the Union, and whatever concerns these personages concerns in some degree the whole Union. When I an ambassador is a party in a suit, that suit affects the welfare of the nation, and a federal tribunal is naturally called upon to decide it. The Union itself may be involved in legal proceedings, and in this case it would be alike contrary to the customs of all nations, and to common sense, to appeal to a tribunal representing any other sovereignty than its own; the federal courts, therefore, take cognizance of these affairs. When two parties belonging to two different states are engaged in a suit, the case cannot with propriety be brought before a court of either state. The surest expedient is to select a tribunal like that of the Union, which can excite the suspicions of neither party, and which offers the most natural as well as the most certain remedy. When the two parties are not private individuals, but states, an important political consideration is added to the same motive of equity. The quality of the parties, in this case, gives a national importance to all their disputes; and the most trifling litigation of the states may be said to involve the peace of the whole Union.[146] The nature of the cause frequently prescribes the rule of competency. Thus all the questions which concern maritime commerce evidently fall under the cognizance of the federal tribunals.[147] Almost all these questions are connected with the interpretation of the law of nations; and in this respect they essentially interest the Union in relation to foreign powers. Moreover, as the sea is not included within the limits of any peculiar jurisdiction, the national courts can only hear causes which originate in maritime affairs.