Common-law marriages are not invalidated by this chapter. Declarations of marriage pursuant to 40-1-311 through 40-1-313, 40-1-323, and 40-1-324 are not invalidated by this chapter.
Mont. Code Ann. § 40-1-403, under Validity of Marriages -- Declaration of Invalidity.
Mont. Code Ann. § 40-1-403
Common-law marriages are not invalidated by this chapter. Declarations of marriage pursuant to 40-1-311 through 40-1-313, 40-1-323, and 40-1-324 are not invalidated by this chapter.