When King Magnus had succeeded in ending the conflict with Scotland, he turned his whole attention to the improvement of the domestic affairs of the country. He undertook a thorough revision of the laws, and, on account of his efforts in this direction, was given the surname _lagaböter_, _i.e._, law-mender. He had a common code of laws compiled for the whole country, while formerly there had been four different laws administered respectively at the four Things; viz., the Frosta-Thing for the Throndhjem country, the Gula-Thing for the western coast, the Eidsiva-Thing for the Uplands, and the Borgar-Thing for the country around Viken. The new general law, as codified by King Magnus, remained in force for nearly four hundred years, and some of it is law even yet. Among the new provisions was the one that, in the future, changes in the laws were to be made only by the king and his "good men" at a state meeting or state council. Thus the Things were deprived of the privilege to make laws.
Magnus also compiled a law for the cities and towns, and a new court law (_Hirdskraa_) for his vassals and courtiers. This court law prescribed rules for the proclamation of kings and described the duties and rights of the courtiers, liegemen, etc. Among new offices created were those of ensign (bearer of the colors), the chancellor, who kept the royal seal, and the master of ceremonies.
Toward the bishops King Magnus was very submissive. At a meeting in Tunsberg, in 1277, he made a number of humiliating concessions to the ambitious Archbishop Jon the Red. Thus the king agreed to abstain from all interference in the selection of bishops, and surrendered to the latter the right of filling all clerical offices.
King Magnus granted the city of Lubeck and other North-German cities--the Hanseatic League--a number of commercial privileges in Norway, and from that time a great part of the commerce of Norway gradually came to be controlled by the Hansa towns.
In his legislation, King Magnus showed a disposition to abandon former democratic characteristics of the institutions. He was fond of pomp and ceremony, and adopted foreign, especially English, court customs. In 1277 he ordained that the liegemen were to be called barons, and the court officials, knights and squires. They were given a partial immunity from taxes, but were to render additional services to the king in case of war. The knights and their families soon began to adopt coats-of-arms, and a kind of nobility was gradually formed.