Excommunication 

Excommunication, as practiced by the Druids, forbade the excommunicated person from accessing the Altars or the performance of religious rites.  It also forbade all intercourse with that person's friends, family, and countrymen. (See "The History of Freemasonry" by Mackey page 200)

The Catholic Church still seems to practice Excommunication, as do the Amish who call it Shunning.  The Amish practice excommunication, but it does not seem to include the transaction of business with countrymen, only with other Amish.

I do not know if excommunication by the Catholic Church means that the excommunicated person is no longer a Catholic.