The Statutes of Blood Pureness (Estatutos de Limpieza de sangre) are not from 1447 but from 1547. They were instituted by the archbishop of Toledo, cardinal Martíndz Guijarro, and they were relatively controversial in its own time. Many civil servants had been or were of Jewish or morisco ancestry, or had been actual Jews like Luis de Santángel, who had been chief accountant of the Crown of Aragon, and treasurer general of the Holy Brotherhood in Castile. He was not the only one. Andrés Cabrera, one of the top officers of Queen Isabel was of Jewish ancestry, and his relative Abraham Seneor was Jewish himself.

The Statutes were of unequal enforcement throughout the realms, and even throughout the cities, the most notable case being Burgos, where the Commercial Consulate had its see, and were a hefty percentage of the town councillors and officers were of converso ancestry. So much so that the Constable of Castile actually threatened Martínez Guijarro that if he wanted to enforce the Statutes in Burgos he would have to do so at the head of an army. The notable lineages of Enzinas, Cartagena, Salamanca, Santa Cruz and many others remained safe and in office in Burgos thanks to the protection of the Constables of Castile.

The humanity of the natives, and the question of the legality and the legitimacy of the Spanish conquest of the Americas did not really have much to do with the Statutes of Blood Purity. The Spanish Jews and Muslims were undeniable human, though not christians, but the natives of America were seen as a different problem altogether, as they were actual pagans and of very different backgrounds and development. Furthermore, Queen Isabel had considered them as much subjects of the Crown as the inhabitants of Castile. However, the monarchs considered they had the duty to christianise them as per the pontificial bulls issued by pope Alexander VI. This led to the development of the encomiendas, that can be seen as a transitional status between the "uncivilised" situation and the christianisation of the territory that should lead them to be subjects of the Crown of actually equal terms to to those in the Iberian Peninsula. Of course, this is was the intent, but not the result. The encomiendas became a system of pseudo-slavery, which eventually caused to be abolished.

Out of pure pragmatism, the Crown promoted the marriage of Spaniards and natives most notably from 1514 onwards. The marriage of Spaniards to the local aristocracies should result in local rulers of Spanish origin with the local legitimacy of being related to the traditional ruling classes. The native aristocrats that co-operated with the Spanish conquest and subsequently with the Spsnish viceroyal administration got rewarded with letters patent of nobility, public offices, etcetera.