Legislators have altered nine ballot initiatives in five states and D.C. since 2017

Legislative alteration is an action by lawmakers at the local or state level to directly amend or repeal a citizen initiative that was approved by voters. Legislative alteration is also called legislative tampering or legislative intervention.
State legislators in Oklahoma, Utah, Washington are currently considering bills to legislatively alter initiatives passed in 2018.
In 2018, Ballotpedia tracked two instances of legislative alteration:
* an ordinance in the District of Columbia overturning Initiative 77 (June 2018), an initiative to increase the minimum wage for tipped workers; and
* a bill in Utah to repeal and replace Proposition 2, the medical marijuana initiative approved in November 2018.
In 2017, Ballotpedia tracked seven initiatives in four states that were repealed or amended through legislative alteration. Most of the affected initiatives were approved by voters in 2016. There were also proposed bills for legislative alteration of two additional initiatives, one in Oklahoma and one in Maine. The bill in Maine was to delay the implementation of a 2016 ranked-choice voting initiative and was approved by the legislature and signed by the governor. But the legislative alteration attempt was prevented through a successful veto referendum petition targeting the bill. Voters overturned the bill in June 2018.
Eleven of the 21 states that feature the initiated state statute power have no restrictions on how soon or with what majority state legislators can repeal or amend initiated statutes. Four states have restrictions on how soon state legislators can repeal or amend initiative statutes—ranging from two to seven years. Six states have restrictions on how large of a supermajority vote is required in the legislature to repeal or amend initiative statutes. Two of these states have restrictions both on how soon and with what majority state legislators can repeal or amend initiative statutes.
California and Arizona are the only two states with voter approval requirements for changes to or the repeal of citizen-initiated state statutes. South Dakota voters rejected an initiated constitutional amendment at the November 2018 ballot that would have enacted a voter approval requirement like in California and Arizona, among other provisions related to campaign finance requirements, lobbying rules, an ethics commission, and other initiative and referendum rules.
The last time voters approved a measure to enact restrictions on legislative alteration was in 2004, when Nebraska voters approved Measure 418. Measure 418 was an initiated constitutional amendment that required a two-thirds supermajority vote in the legislature to amend or repeal initiated state statutes. Colorado voters rejected initiatives in 2006 and 2008 that would have restricted legislative alteration, among other changes to the state’s initiative process.
Legislative alteration does not apply to initiated constitutional amendments but only to initiated state statutes. This is because constitutional amendments proposed by the state legislature must be put before voters for ratification in every state but Delaware. Thus, state legislators cannot directly amend initiated constitutional amendments themselves. However, the implementation of initiated constitutional amendments through statutes passed by the legislature are sometimes criticized by initiative proponents as incompatible with the purpose of the initiative. Moreover, deals, compromise legislation, or certain legislative actions can result in policies proposed through successful citizen initiative petitions being changed or prevented without the initiatives themselves ever going on the ballot. In 2018, there was a higher-than-usual number of compromises and legislative actions precluding elections on citizen initiatives.