What is Advocati Fisci?

Legal Definition
In the civil law. Advocates of the fisci or revenue; fiscal advocates, (qui causam fisc egissent.) Cod. 2, 9, 1; Id. 2, 7, 13. Answering, in soine measure, to the king's counsel in English law. 3 Bl. Comm. 27.
-- Black's Law Dictionary