Dear Leon:

At one time a Cardinal could be a layman, but not today. I believe the last Lay Cardinal was Cardinal Giacomo Antonelli (1808-1876) who was raised up to the dignity of cardinal deacon in 1847 by Pope Pius IX. He was in minor orders but never ordained a deacon or priest.

There were several deacons who were Cardinals but never ordained into the priesthood. The last of those I believe was Carlo Cristofuri (1813-1891).

Today, since the pontificate of John XXIII (1958), a candidate for Cardinal must be a priest (cic 351.1), but not necessarily a bishop. If a non-bishop priest is appointed a Cardinal he will be ordained a bishop.

As for the Papacy, theoretically an ordinary layman can be elected. In fact it has happened more than once.

Although there are some discrepancies in histories from what I can gather the first layman elected Pope was either Leo VIII (963) or Benedict VIII (1012). The last layman elected Pope was Callixtus III (1455).

The last non-bishop elected Pope was Gregory XVI (1830) and the last non-Cardinal was Urban VI in 1378

The procedure is that if a layman were elected Pope he would be ordained a deacon, priest, and bishop essentially all in one day.

A Pope does not have to be a Cardinal, but he does have to be a bishop. Current Canon Law (cic. 312.1) states that if an elected Pope is not a bishop, he will be ordained a bishop immediately.

There has been at least one Pope, however, who was a layman and never ordained. Following the death of Pope Innocent V in 1276, and after a drawn out conclave, the electors chose Cardinal Ottobono Fieschi (Pope Adrian V), a successful and highly respected papal diplomat, and a layman. Pope Adrian V ruled from July 11 to Aug. 18, 1276, but died without ever being ordained priest or bishop.

As for who elects a Pope, since the Third Lateran Council (1179) the electors of a Pope were reserved to Cardinals.

God Bless,
Bro. Ignatius Mary