Of councel : OBS – A phrase commonly applied in practice ... particularly to one employed to assist in the preparation or management of an action, or its presentation on appeal, but who is not the principal attorney of record for the party. - Black's law dictionary : definitions of the terms and phrases of American and English jurisprudence, ancient and modern

aussi (même source) : pour avocat - OBS – A phrase commonly applied in practice to the Counsel employed by a party in a cause, and particularly to one employed to assist in the preparation or management of an action, or its presentation on appeal, but who is not the principal attorney of record for the party. Source
OBS – ... anglicisation of the law latin "a consiliis" ...

avocat-conseil - DEF – Avocat qui borne lui-même son activité à la consultation à l'exclusion de la plaidoirie.

et avocat :
- DEF – Auxiliaire de justice qui fait profession de défendre, devant les cours et tribunaux, les intérêts de ceux qui lui confient leur cause [...]

(Vocabulaire juridique
Paris : Presses universitaires de France, ©1987)