In old English law. A suit or action. Thus, the power to “hold pleas” is the power to take cognizance of actions or suits; so “common pleas” are actions or suits between private persons. And this meaning of the word still appears in the modern declarations, where it is stated, e. g., that the defendant “has been summoned to answer the plaintiff in a plea of debt.”
Source: Black’s Law Dictionary 2nd Ed (1910)
