In the late 18th century, some mixed-race persons sought legal "certificates of whiteness" ("cédulas de gracias al sacar"), in order to rise socially and practice professions. American-born Spaniards ("criollos") sought to prevent the approval of such petitions, since the "purity" of their own whiteness would be in jeopardy. They asserted their "purity of blood" ("limpieza de sangre") as white persons who had "always been known, held and commonly reputed to be white persons, Old Christians of the nobility, clean of all bad blood and without any mixture of commoner, Jew, Moor, Mulatto, or converso in any degree, no matter how remote." Spaniards both American- and Iberian-born discriminated against pardos and mulattoes because of their "bad blood." One Cuban sought the grant of his petition in order to practice as a surgeon, a profession from which he was barred because of his mulatto designation. Royal laws and decrees prevented pardos and mulattoes from serving as a public notary, lawyer, pharmacist, ordination to the priesthood, or graduation from university. Mulattas declared white could marry a Spaniard.