Book of medieval Norwegian laws
The Hirdskraa ("Hirðskrá"), 'The book of the hird', is a collection of laws regulating many aspects of the royal hird of late 13th century Norway. Compiled somewhere in the first part of the 1270s at the order of King Magnus VI (r. 1263-1280), it was recopied widely in the 14th century. The earliest extant texts, the AM 322 fol. and NkS 1642 4to (in the Royal Library, Copenhagen), date to around 1300. AM 322 fol. is thought to have originated at the court of King Magnus' son Håkon V's chancellery in Oslo. In the mid-14th century, with the Norwegian kingdom falling into a personal union with first Sweden and then Denmark, the text was copied less in Scandinavia but remained popular in Iceland, where copies exist from as late as the 18th century. The text can be set beside a number of comparable sections in the "Konungs Skuggsjá" .
The Hird.
The king’s hird (Old Norse "hirð", from Old English "hired") was more than just a bodyguard and a circle of advisers. Some historians discuss the concept of the corporative hird, where the king functions, at least in theory, as the first among equals at the upper levels of the hird. The hird also formed the professional core of the Norwegian army as maintained by the king.
Contents.
The text of "Hirdskraa" can be more or less conveniently divided into three parts. 
Interpretation.
The "Hirdskraa" was probably more of a guide-book than a strictly interpreted law on how the hird was to function. Many of the incorporated concepts, such as the Norwegian jarl being clearly subordinate to the king (as opposed to more of an allied subordinate as the jarls of the islands within the Norwegian realm) do not always reflect historical facts. It must also be regarded as the Norwegian king's attempts to create a more solid administration for their realm in the 13th century. This is especially true of the reign of Håkon V, who, in contrast to his father, seems to have wanted the hird to lose its corporative nature and be put directly under the king.