Mont. Code Ann. § 72-9-107

Upon death of a married person, one-half of the property to which this part applies is the property of the surviving spouse and is not subject to testamentary disposition by the decedent or distribution under the Uniform Probate Code. One-half of that property is the property of the decedent and is subject to testamentary disposition or distribution under the Uniform Probate Code. With respect to property to which this part applies, the one-half of the property which is the property of the decedent is not subject to the surviving spouse's right to elect against the will.