Abstract
The article observes concepts of “Law”, “Custom”, “Usage”, and “Fuero” in the “Siete Partidas” of Alphonse X the Wise, a king of the Castile-Leon Kingdom from 1252 to 1284. In the first part, the author gives an overview of the legislative situation in the Castile-Leon Kingdom just before the reign of Alphonse X. He stresses that the king would justify the tremendous territorial gains made by his father, Fernando III, and Alphonse himself. Thus, the composition of one of the largest law codes in Europe was a part of his costly and full project. The second part of the article contains some explanations about the concept of “custom” in the Alphonsine legislation. The author analyses procedures of apparition of the custom, its being, and cancellation. The author gives particular place in his theory to the Roman Law, or, more precisely, to the Ius commune. Finally, the third part of the article contains translation into Russian of two first chapters of Partidas.