Montana Constitution, Article XI
Section 3. Forms of government. (1) The legislature shall provide methods for governing local government units and procedures for incorporating, classifying, merging, consolidating, and dissolving such units, and altering their boundaries. The legislature shall provide such optional or alternative forms of government that each unit or combination of units may adopt, amend, or abandon an optional or alternative form by a majority of those voting on the question.
(2) One optional form of county government includes, but is not limited to, the election of three county commissioners, a clerk and recorder, a clerk of district court, a county attorney, a sheriff, a treasurer, a surveyor, a county superintendent of schools, an assessor, a coroner, and a public administrator. The terms, qualifications, duties, and compensation of those offices shall be provided by law. The Board of county commissioners may consolidate two or more such offices. The Boards of two or more counties may provide for a joint office and for the election of one official to perform the duties of any such office in those counties. 