Hi, Steve —

That's a good question!

When Eastern Rite Cardinals meet with other cardinals or con-celebrate the liturgy, they generally wear their own vestments. On the other hand, if a bi-ritual priest celebrates the liturgy, not native to him, he uses the other rite's vestments. Someone elected pope is the bishop of Rome, so presumably he would celebrate henceforth as bishop of Rome, i.e., Latin Rite. Since we haven't run into this situation in modern times (and probably don't have sufficient records when it did happen, which I think it did) they would probably have to make some new decisions about it, much like they did with Pope Benedict's resignation.

My guess is he would wear Western vestments when celebrating a Latin-rite Mass. As for his white cassock, I'm not sure. On the one hand that's kind of unique to the pope and in a class by itself, but then again it is based on Latin-rite dress.

Maybe the pope would like to retain some of his Eastern heritage. I don't know, I think that would be up to him.

Eric