Mont. Code Ann. § 30-11-111

An agreement for the sale of real property or of any interest in real property is not valid unless the agreement, or some note or memorandum of the agreement, is in writing and subscribed by the party to be charged or the party's agent authorized in writing. However, this does not abridge the power of any court to compel the specific performance of any agreement for the sale of real property in case of part performance of the agreement.