Add to ORKGREAPPORTIONMENT. SENATE DISTRICTS. REFERENDUM STATUTE. State Senate districts are reapportioned every ten years following the federal census. Chapter 536 (SB 99), enacted by the 1981 Legislature, revises boundaries of the 40 Senate districts. It also imposes time and other limitations on all redistricting court challenges. This referendum petition, if signed by the required number of electors and filed with the Secretary of State within 90 days of the enactment of SB 99, will: (1) Require that this statute be placed on the ballot at an election, and (2) Prevent the statute from taking effect unless it is adopted by majority vote