The Corner has an item on politician excommunication. Apparently, the last time it happened was in New Orleans in 1962. Three politicians defied the Archbishop's order to integrate the parochial school system and were excommunicated for it.
Two days later, President John F. Kennedy was asked at a press conference, "Mr. President, would you care to comment on developments in New Orleans where the Archbishop excommunicated three people for hindering school desegregation?"He replied: "No, the action of the Archbishop related to private acts and private individuals, which did not involve public acts or public policy, so that carrying out the spirit of the Constitution which provides a separation between church and state, I think it would be inappropriate for me to comment on that."