(a) The credibility of a witness may be attacked by any party, including the party calling the witness. (b) No party is bound by the testimony of any witness.
Who May Impeach; Party Not Bound By Testimony
Mont. Code Ann. tit. 26, ch. 10, Rule 607, under Article VI. Witnesses.
Mont. Code Ann. tit. 26, ch. 10, Rule 607