Idaho constitution
Article XVIII
Section 12

The
legislature by general law may provide for optional forms of county government for
counties, which shall be the exclusive optional forms of county government. No
optional form of county government shall be operative in any county until it has
been submitted to and approved by a majority of the electors voting thereon in the
county affected at a general or special election as provided by law. The electorate
at said election shall be allowed to vote on whether they shall retain their present
form of county government or adopt any of the optional forms of county
government. In the event an optional form shall be adopted, the question whether
to return to the original form or any other optional form, may be placed at
subsequent elections, but not more frequently than each four years. When an
optional form of county government has been adopted, the provisions of this section
supersede sections 5, 6 and 10 of this article and sections 16 and 18 of article V.