A Fascinating Hypothetical

Can an excommunicated cardinal be allowed to participate in a conclave?  Civil and common lawyers will not be surprised to learn that the canon lawyer's answer is an answer they are very familiar with indeed:

"It depends."

You can find out what it depends on here.

(And by the way, it punctures a few holes in some sede vacantist arguments.  And, yes, I am aware we are all sede vacantists at the moment.  But I mean those who are more or less permanently so.)