CONGRESS (Lat. congressus, coming together, from congredi; cum, with, and gradus, step), in diplomacy, a solemn assembly of sovereigns or their plenipotentiaries met together for the purpose of definitely settling international questions of common interest. In this political connotation the word first came into use in the 17th century; an isolated instance occurs in 1636, when it was applied to the meeting of delegates summoned by the pope to Cologne, to attempt to put an end to the Thirty Years’ War. In 1647 the meetings of delegates for the conclusion of peace, assembled at Osnabrück and Münster, were termed a congress; and in spite of objections to it on the ground that it was “coarse and inappropriate,” based on the physiological sense of the word, it continued thenceforward in use.

The adoption of the name Congress for the national legislative body in the United States (and so for other American countries) was simply a development from this usage, for the “Continental Congresses” of 1774 and 1775–1781, and the “Congress of the Confederation” (1781–1788), were, as inter-state representative deliberative bodies, analogous to international congresses, and the Congress of 1789 onwards ultimately consists of representatives of the sovereign states composing the Union; this body is, however, dealt with under United States: Political Institutions. The more general analogous use of the term (Church Congress, &c.) is of modern origin.

In its international sense the term “congress” is only applied to gatherings of first-class importance, attended either by the sovereigns themselves or by their secretaries of state for foreign affairs; less important meetings, e.g. either in preparation for a congress or for the settlement of a particular question, are usually termed “conferences.” The dividing line between the congress and the conference is, however, historically ill-defined; and though a congress of the first importance, e.g. that of Vienna (1814–1815), is never otherwise described, the two terms have often been used indifferently in official diplomatic correspondence even of such dignified assemblages as the meetings of sovereigns and statesmen at Aix-la-Chapelle (1818), Troppau (1820) and Laibach (1821). The individual sessions of a congress are also sometimes called conferences.

The results of the work done at various international congresses in developing a sense of the common interests of nations are dealt with under International Law and its allied articles. The more important congresses, e.g. Münster and Osnabrück (Westphalia) in 1648; Breda, 1667; Aix-la-Chapelle, 1668, 1748, 1818; Nijmwegen, 1678; Regensburg, 1682; Ryswick, 1697; Utrecht, 1713; Tetschen, 1779; Paris, 1782, 1814, 1815, 1856; Rastadt, 1794; Amiens, 1802; Chatillon, 1814; Vienna, 1814–1815; Troppau, 1820; Laibach, 1821; Verona, 1822; Berlin, 1878, are treated under their topographical headings. The present article is concerned only with the questions of constitution and procedure.

Convocation and constituent Elements of a Congress.—Any sovereign Power has the right to issue invitations to a congress or conference. In principle, moreover, every state directly concerned in the matters to be discussed has the right to be represented. But this principle, though affirmed by the Powers at Aix-la-Chapelle in 1818, has rarely been translated into practice. At the congress of Vienna (1814–1815), the decisions of which affected every state in Europe, a committee of the five great Powers claimed and exercised the right to settle everything of importance; and this set the precedent which has been followed ever since. At the congresses of Paris and Berlin, as at that of Vienna, the great Powers regulated the affairs of lesser states without consulting the representatives of the latter. Similarly, at the conference of 1869 on the affairs of Crete no representative of Greece was present; and at the conference of London (1883), on the international regulation of the Danube, the sovereign state of Rumania, though a Danubian Power, was not represented. It was only with great difficulty that Cavour obtained admission to the congress of Paris in 1856, and the proposal of a congress in 1859 broke down on the refusal of Austria to admit the right of Sardinia to be represented. M. Pradier-Fodéré deplores the consistent breach of the “fundamental rule” in this respect; but since every sovereign state, great and small, once admitted, has an equal voice, it is difficult to see how a principle, equitable in theory, could be established in practice. The failure of the Hague conferences to arrive at any substantial results was in fact due, more than anything else, to the admission on equal terms of a crowd of very unequal Powers. It may then be laid down that all congresses and conferences that have effected settlements of importance have been summoned and dominated by Powers strong enough to enforce respect for their views.

Preliminaries.—Before a congress meets it is customary, not only to agree on the place of meeting (a question often of first-class importance) and on the Powers to whom invitations are to be sent, but to define very carefully the nature and scope of the business to be transacted. This is done sometimes by an elaborate exchange of diplomatic correspondence issuing in preliminary conventions, sometimes by the summoning of conferences, e.g. those at Vienna in 1855 preliminary to the congress of Paris in 1856.

Procedure.—When the congress assembles the first business is the verification of powers, which is done by a. commission specially appointed to examine the credentials of the plenipotentiaries. It is usual for the Powers, for obvious practical reasons, to be represented by two or three plenipotentiaries. If the foreign minister himself attend, he needs no credentials; those of his colleagues are countersigned by him. The verification being completed, questions of procedure, of precedence and the like, are settled. In earlier times this was a matter of extreme difficulty and delicacy, since there was no norm by which the respective dignity of the representatives of first-class Powers could be established; an incredible amount of time was wasted in futile questions of precedence, and not seldom negotiations for a peace that every one desired broke down on a point of etiquette. All this has been obviated by the rule observed at the congress of Berlin (1878), according to which the plenipotentiaries took their seats at a horse-shoe table in the alphabetical order of the states they represented, according to the French alphabet.

The presidency of the congress is by courtesy reserved for the minister for foreign affairs of the state in which the meeting is held; if, however, he decline to serve, a president is elected; or, if there be a mediating Power, the minister representing this presides. At the first session the president takes his seat and delivers a speech welcoming the delegates and sketching the objects of the meeting; the bureau of the congress (secretary, assistant secretaries, and archivist) is then elected on the nomination of the president, and its members are introduced to the assembly. Finally the president impresses on all present the obligation of keeping the proceedings secret, and adjourns the session for a day or two, in order that the ministers may have an opportunity of making each others’ acquaintance and talking matters over in private. Serious business begins with the second session.

The discussions are governed by carefully defined rules. Thus every proposition must be presented in writing, and all decisions to be binding on all must be unanimous. The secretary keeps the minutes (procès-verbal) of each session, which are signed by all present and read at the next meeting. This protocol—as it has been called since the congress of Vienna-takes the form of a bald, but very exact résumé of important points discussed, ending with a record of the conclusions and resolutions arrived at. If there be no such results, opinions are recorded. If any plenipotentiary dissent from the general opinion, such dissent must be recorded in the protocol. Sometimes short signed memoranda, known as a vote or opinion, are attached to the protocol, stating the reasons that have governed the Powers in question in agreeing to a given conclusion. Individual Powers may express their dissent in two ways: either by placing such dissent on record, as Lord Stewart did at Laibach, or by withdrawing altogether from the sessions of the congress, as Spain did at Vienna and Great Britain at Verona. Though the Final Act of Vienna was issued as the act of all the Powers, the subsequent formal adhesion of Spain was considered necessary to complete the “European” character of that treaty; the action of Great Britain at Verona prevented the intervention in Spain from having the sanction of the concert. At Vienna in 1814, owing to the vast range of the questions to be settled, the work of the congress was distributed among committees; but at Paris (1856) and Berlin (1878) all matters were discussed and settled in full session. The conclusions arrived at after the discussion of the various subjects before the congress are usually embodied in separate conventions, duly signed by the Powers who are a party to them. Finally, these separate conventions are brought together in an inclusive treaty, signed by all the plenipotentiaries present, known as the Final Act.

See P. Pradier-Fodéré, Cours de droit diplomatique (2 vols., 2nd ed., Paris, 1899).  (W. A. P.)