Section 3. Supreme court organization. (1) The supreme court consists of one chief justice and four justices, but the legislature may increase the number of justices from four to six. A majority shall join in and pronounce decisions, which must be in writing.
     (2) A district judge shall be substituted for the chief justice or a justice in the event of disqualification or disability, and the opinion of the district judge sitting with the supreme court shall have the same effect as an opinion of a justice.