One of the leading characteristics of Spanish government in the sixteenth century was its interest in legal codification. In the sphere of colonial administration, particularly, a number of impressive codes were compiled, of which the most important were the New Laws of 1543, regulating the relations between the Indians and their conquerors; the Ordinances on Discoveries of 1573, laying down the conditions of future exploration and settlement; and the Ordinances of the Audiencias, which were promulgated at Monzón in 1562 and which for the sake of brevity may be called the Ordinances of Monzón.

The Ordinances of Monzón were designed to organise the audiencias of the Indies (except the two viceregal audiencias, which were necessarily different in constitution and powers) according to a common pattern, and so to counteract the growing influence of local custom in the various provinces. They applied originally to the two new audiencias of Quito and Los Charcas and were subsequently extended to cover the other lesser audiencias. When the audiencia of New Galicia was reorganised in 1572 and declared independent of the audiencia of Mexico, it received the Ordinances of Monzón as its charter in place of the original loosely worded and experimental ordinances of 1548.

A closer definition of powers and duties was badly needed. The authority of the audiencia, like that of most other administrative organs in a centralised empire, rested not upon local support but upon royal appointment and the letter of royal decrees.