States have adopted various policies relating to voter and legislature requirements for constitutional amendments.
See additional table for a list of 2022 Initiative Petitions in Missouri and the US.
See our related Science Notes on Initiative Petition Process and Impacts.
Table 1. States with a time limit after an initiative is passed before the legislature may alter or repeal the initiative.
| State | Citation | Alteration time limit |
| Alaska | AK Const. Art. 11, § 6 | Two years |
| Nevada | N.R.S. Const. Art. 19, § 2 | Three years |
| North Dakota | NDCC Const. Art. 3, § 8 | Seven years (or two-thirds vote prior to seven years) |
| Washington | RCWA Const. Art. 2, § 1 | Two years (or two-thirds vote prior to two years) |
| Wyoming | Const. Art. 3, § 52 | Two years |
Table 2. States with different voter requirements for constitutional amendments.
| State | The requirement to alter the constitution |
| Colorado | 55% of voters must approve |
| Florida | 60% of voters must approve |
| Nevada | Only a majority is needed, but it must be approved in two consecutive elections |
| Illinois | Either 60% of voters must approve, or a majority of those voting in the election as a whole |
Table 3. States with supermajority requirements for legislatures to ballot initiatives.
| State | Citation | Supermajority Requirement |
| Arizona | A.R.S. Const.Art. 21 § 1, Part 6 | May amend the initiative with three-fourths vote, but may only amend to “further the purpose” of the measure. |
| Arkansas | Arkansas Const.Art. 5 § 1 | Two-thirds vote to amend or repeal. |
| Michigan | MI Const.Art. 2, § 9 | May be amended or repealed only by three-fourths of each house or by a vote of the electors. |
| Nebraska | Ne.Rev.St. CONST.Art. III, § 2 | Two-thirds vote to amend or repeal. |
| North Dakota | NDCC Const.Art. 3, § 8 | Two-thirds vote (or majority after seven years). |
| Oregon | OR CONSTArt.II, § 23;Art. IV, § 1 | Supermajority vote only to change vote requirement. |
| Washington | RCWA Const.Art. 2, § 1 | Two-thirds vote (or majority after two years). |
*NOTE: This memo was written in response to a specific legislator request and is meant to supplement the research contained in the following full Science Notes: Initiative Petition Process and Initiative Petition Impacts.
