Pope Sixtus V fixed the number of Cardinals at seventy in his bull of 1587; Bl John XXIII first exceeded this limit in 1958. In 1970, Paul VI established a cut-off age of 80 for Cardinals, above which, while retaining their Cardinatial rank, they could no longer vote in a Conclave; and in 1973 he limited the number of Cardinal-electors to 120.
Now, bishops are required to submit their resignation to the Roman Pontiff when they turn 75, and he may choose to accept these resignations (indeed, he may himself choose to abdicate, as recent events have demonstrated). So it seems somewhat odd that a Cardinal may still vote to elect a Pope, when that same Cardinal, though under 80, is over 75, and has submitted his own resignation from whatever other ecclesiastical office he may hold (such as Archbishop of a see, or head of some curial department), let alone if that resignation has been accepted.
Would it not, then, seem more reasonable to drop the cut-off age for Cardinals by five years, so that, when the Roman See falls vacant, only those not yet 75 years old may vote? This would have an additional advantage, in that all the pairs of Cardinal-electors, one of whom holds a position, and the other held the same position but is now, for instance, Archbishop or Prefect emeritus, would cease to exist.
Furthermore, a simple calculation demonstrates that such a reduction would reduce the number of Cardinal-electors at present to 66, within the old limit of seventy that endured from Tridentine to modern times. It may be argued that 120 is too unwieldy a number.
The main problem with this change would be that it would clear out all but one of the Cardinal-bishops, and all of the holders of the seven suburbicarian sees. It would be necessary to make a new provision, whereby Cardinal-bishops of those sees who pass their 75th birthday should thereafter become emeritus holders of those titles, while the Pope could create new Cardinal-Bishops to have the title of the suburbicarian sees. Similarly, rather than the clumsy rule whereby the Dean and Vice-Dean of the College of Cardinals hold office indefinitely, and – as this year – neither may be eligible to attend the Conclave, they too ought resign their positions when they turn 75, and new ones be chosen.
I am conscious of the fact that Benedict XVI would have been ineligible to attend the Conclave of 2005 under these rules; but the Cardinal-electors are under no obligation to choose one of their own, and the Italian newspapers have seriously suggested that in this upcoming Papal election the Cardinals could elect one of the non-voting Cardinals.
A smaller, slightly younger Conclave could well represent the sort of sane, conservative reform measure that the next Pope may consider implementing. It would not represent a major shift, but could send an important signal.