Query: In what year was it declared that Cardinals had to be bishops?
Context: For example, in the 16th century, Reginald Pole was a cardinal for 18 years before he was ordained a priest. In 1917 it was established that all cardinals, even cardinal deacons, had to be priests, and, in 1962, Pope John XXIII set the norm that all cardinals be ordained as bishops, even if they are only priests at the time of appointment. As a consequence of these two changes, canon 351 of the 1983 Code of Canon Law requires that a cardinal be at least in the order of priesthood at his appointment, and that those who are not already bishops must receive episcopal consecration.