Teodolfo Mertel, the last man to have been created cardinal without first having been ordained a deacon. He was ordained to the diaconate in 1858, a few months after becoming a cardinal.
In the historical practice of the Catholic Church, a lay cardinal was a man whom the pope appointed to the College of Cardinals while still a layman. This appointment carried with it the obligation to be ordained to a clerical order,[1] meaning that "lay cardinal" was not a permanent state, but a term in reference to a man who was appointed cardinal prior to taking on the clerical state corresponding to that appointment.[2]
The current law of the Catholic Church is that a man must be first ordained at least a priest in order to be considered for appointment as a cardinal.[3]
In 1917, Pope Benedict XV promulgated the first edition of the Code of Canon Law, which included a provision that a man must be first ordained a priest prior to being considered for appointment as a cardinal.[11]
^Cartwright, William Cornwallis (1868). On Papal Conclaves. Edinburgh: Edmonston and Douglas. p. 123. Laymen were named Cardinals only for twelve months, being bound within that period to take Deacon's orders
^Cartwright, William Cornwallis (1868). On Papal Conclaves. Edinburgh: Edmonston and Douglas. pp. 121–122. In all these cases, however, it is clear that some orders had been taken; and therefore, in the strict sense of the term, these Cardinals were no longer laymen.
