3.05.06. An advocate shall not personally act in a dispute if he knows or if it is evident that he will be called upon as witness.
However, he may accept or continue to act if the fact of not doing so is of a nature to cause serious and irreparable harm to the client, or if his testimony only refers to:
(a) an uncontested matter;
(b) a question of form and where there is no reason to believe that serious proof shall be offered to contradict such testimony;
(c) the nature and value of the professional services he or another person engaging in his activities within the same partnership or joint-stock company have rendered to the client.
R.R.Q., 1981, c. B-1, r. 1, s. 3.05.06; O.C. 351-2004, s. 39.