What is Brocard?

Legal Definition
A brocard is a legal principle expressed in Latin (and often derived from past legal authorities or Roman Law), which is traditionally used to express concisely a wider legal concept or rule. The name comes from the Latinized name of Burchard (died 1025), bishop of Worms, Germany, who compiled 20 volumes of Ecclesiastical Rules.
-- Wikipedia
Legal Definition
In old English law. A legal maxim. "Brocardica Juris," the title of a small book of legal maxims, published at Paris, 1508.
-- Black's Law Dictionary