2-16-403. Salaries of supreme court justices. Prior to June 30 of each even-numbered year, the department of administration shall conduct a salary survey of justices and chief justices of the highest appellate courts similar to the Montana supreme court for the states of North Dakota, South Dakota, Wyoming, and Idaho. The department shall include the salary for a Montana supreme court justice or the chief justice in determining the average salary for a justice and the average salary for the chief justice. If the average salaries are greater than the salaries for a supreme court justice or the chief justice in Montana, then beginning July 1 of the year following the year in which the survey is conducted, the average salaries are the new salaries for a supreme court justice or the chief justice. A justice's salary or the chief justice's salary may not be reduced.