Mont. Code Ann. § 28-2-401
28-2-401 When apparent consent not free
28-2-401 . When apparent consent not free. (1) An apparent consent is not real or free when obtained through:
(a) duress;
(b) menace;
(c) fraud;
(d) undue influence; or
(e) mistake.
(2) Consent is deemed to have been obtained through one of the causes mentioned in subsection (1) only when it would not have been given had such cause not existed.