Latin phrases used to be an important part of a lawyer’s armoury, if only to confuse those without a classical education into believing that a mundane set of words must be important because of the solemnity with which they were intoned. Doubtless this also justified instructing a lawyer and a fee as the ordinary person could not be expected to act for himself (and in those days it almost invariably was a male) if they could not understand the language used.
I have an affectionate memory of learning Latin although too often my reports complained that “he could do better at Latin sentences if he learned the vocabulary and the conjugations”. I am in favour of it being taught, not least because it is one of the foundations of our own language today. However, nowadays the use of Latin in the law is dying out and a good thing too! Plain English is what we need so that everyone can understand what is being said and written.