Actually, Rich, an excommunication can be administered in two ways:
- as a penalty after a judicial trial (ferendae sententiae)
- declared if incurred automatically by the individual's action (latae sententiae) if he or she violates a law that carries with it the penalty of excommunication.
Schism is one such action. Schism is failure to subject oneself to the Roman Pontiff, or to act in communion with those in communion with the Roman Pontiff. In this case, the bishop is stating that the mystic refuses to subject herself to him - he being the lawful bishop in communion with the Roman Pontiff. This carries an automatic excommunication for schism when the refusal is obstinate and on-going.
For more explanation on this topic, see my article published last summer in This Rock Magazine, "Strong Medicine: Canon Law and Excommunication". Or better yet (shameless plug alert) check out a copy of my new book with Michael Trueman, just recently released, Surprised by Canon Law, Volume 2.