The Constitution of the State of Hawaii Article IV, § 8

The reapportionment commission shall, as part of the reapportionment plan, assign two-year terms for twelve senate seats for the election immediately following the adoption of the reapportionment plan.  The remaining seats shall be assigned four-year terms.  Insofar as practicable, the commission shall assign the two-year terms to senate seats so that the resident population of each senate district shall have no more than two regular senate elections for a particular senate seat within the six-year period beginning in the even-numbered year prior to the reapportionment year;  provided that in the event of a multi-member senate district, the senators elected with the highest number of votes in that district in the election immediately following the adoption of the reapportionment plan shall fill the senate seats in that district which were assigned the four-year terms by the commission.