What is Arbitrios?

Legal Definition
In Spanish and Mexican law. Taxes Imposed by municipalities on certain articles of merchandise, to defray the general expenses of government, in default of revenues from "proprios," i. e., lands owned by the municipality or the income of which was legally set apart for its support Sometimes used in a wider sense, as meaning the resources of a town, including its privileges in the royal lands as well as the texes. Escriche Diet.; Sheldon v. Milmo, 90 Tex. 1, 36 S. W. 413.
-- Black's Law Dictionary