First French Republic in the context of "18 Fructidor"

A constitution, or supreme law, is the aggregate of fundamental principles or established precedents that constitute the legal basis of a polity, organization or other type of entity, and commonly determines how that entity is to be governed.

When these principles are written down into a single document or set of legal documents, those documents may be said to embody a written constitution; if they are encompassed in a single comprehensive document, it is said to embody a codified constitution. The constitution of the United Kingdom is a notable example of an uncodified constitution; it is instead written in numerous fundamental acts of a legislature, court cases, and treaties.

The Constitution of the Year XII (French: Constitution de l’an XII), also called the Organic Sénatus-consulte of 28 Floréal, year XII (Sénatus-consulte organique du 28 floréal an XII), was a national constitution of the First French Republic adopted during the Year XII of the French Revolutionary Calendar (1804 in the Gregorian calendar).

It amended the earlier Constitution of the Year VIII and Constitution of the Year X, establishing the First French Empire with Napoleon Bonaparte — previously First Consul for Life, with wide-ranging powers — as Napoleon I, Emperor of the French. The Constitution established the House of Bonaparte as France's imperial dynasty, making the throne hereditary in Napoleon's family. The Constitution of the Year XII was later itself extensively amended by the Additional Act and definitively abolished with the final return of the Bourbons in 1815.

The Consulate (French: Consulat) was the top-level government of the First French Republic from the fall of the Directory in the coup of 18 Brumaire on 9 November 1799 until the start of the French Empire on 18 May 1804.

During this period, Napoleon Bonaparte, with his appointment as First Consul, established himself as the head of a more autocratic and centralised republican government in France while not declaring himself sole ruler. Due to the long-lasting institutions established during these years, Robert B. Holtman has called the consulate "one of the most important periods of all French history." By the end of this period, Bonaparte had engineered an authoritarian personal rule now viewed as a military dictatorship.

Consul (abbrev. cos.; Latin plural consules) was the title of one of the two chief magistrates of the Roman Republic, and subsequently also an important title under the Roman Empire. The title was used in other European city-states through antiquity and the Middle Ages, in particular in the Republics of Genoa and Pisa, then revived in modern states, notably in the First French Republic. The related adjective is consular, from the Latin consularis.

This usage contrasts with modern terminology, where a consul is a type of diplomat.