Saint-Just, Louis de, 1767-94, French revolutionary. A member of the Convention from 1792, he became a favorite of Maximilien Robespierre and was (1793-94) a leading member of the Committee of Public Safety (see Reign of Terror). As commissioner (1793) with the army of the Rhine, he contributed to the successful operations that drove the allies beyond the French border. On his return he served as president of the Convention. He supported Robespierre in the destruction of the Hébertists and Dantonists (see Hébert, Jacques René; Danton, Georges Jacques); in doctrinaire interpretation of Rousseau's political teachings he was more radically idealistic than Robespierre. Saint-Just believed fanatically in the perfect state, based on rigorous Spartan virtue, and brooked no opposition to this political philosophy. During the coup of 9 Thermidor (1794), which overthrew Robespierre and other members of the Committee of Public Safety, Saint-Just was prevented from delivering a speech in defense of Robespierre. Saint-Just's arrest was ordered, and he was guillotined with Robespierre.

Haüy, René Just, Abbé, 1743-1822, French mineralogist, an authority on crystals. He discovered the geometric law of crystallization and wrote many books and papers on crystallography. He was professor at the Museum of Natural History, Paris, from 1802.

Set of conditions under which a resort to war is morally legitimate (jus ad bellum); also, rules for the moral conduct of war (jus in bello). Among the proposed conditions for the just resort to war are that the cause be just (e.g., self-defense against an attack or the threat of imminent attack), that the authority undertaking the war be competent, that all peaceful alternatives be exhausted, and that there be a reasonable hope of success. Two of the most important conditions for the just conduct of war are that the force used be “proportional” to the just cause the war is supposed to serve (in the sense that the evil created by the war must not outweigh the good represented by the just cause) and that military personnel be discriminated from innocents (noncombatant civilians), who may not be killed. The concept of just war was developed in the early Christian church; it was discussed by St. Augustine in the 4th century and was still accepted by Hugo Grotius in the 17th century. Interest in the concept thereafter declined, though it was revived in the 20th century in connection with the development of nuclear weapons (the use of which, according to some, would violate the conditions of proportionality and discrimination) and the advent of “humanitarian intervention” to put an end to acts of genocide and other crimes committed within the borders of a single state.

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(born Aug. 25, 1767, Decize, France—died July 28, 1794, Paris) French Revolutionary leader. In support of the French Revolution, he wrote the radical Esprit de la révolution et de la constitution de France (1791) and was elected to the National Convention in 1792. A close associate of Maximilien Robespierre and a member of the Committee of Public Safety, he was elected president of the Convention in 1793 and sponsored the Ventôse (March) Decrees, which confiscated property of the Revolution's enemies and redistributed it to the poor. He led the victorious attack against the Austrians at Fleurus (in modern Belgium). A fanatical leader of the Reign of Terror, he was arrested in the Thermidorian Reaction and guillotined.

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