Local Government Act 1993 No 30
Current version for 1 July 2020 to date (accessed 5 August 2020 at 09:54)
228   How is it decided that the mayor be elected by the electors?
(1)  It may be decided at a constitutional referendum that the mayor be elected by the electors.
(2)  A decision that the mayor be elected by the electors takes effect in relation to the next ordinary election after the decision is made.