Proposition 22, a 2020 California ballot measure allowing app-based transportation and delivery services to treat their workers as independent contractors, allows for legislative amendments "consistent with" its purpose—but imposes an unusually high supermajority requirement, seven-eighths of the legislature, and the governor's signature.
California is one of only two states requiring voter approval to change or overturn an existing measure—"unless a provision in the initiative explicitly allows for legislative alteration." In 11 of the 21 states that permit citizen-initiated ballot initiatives, there are no restrictions on when and how state legislatures can repeal or amend the statutes. Some states limit how soon state legislatures can repeal or amend (i.e., after two years); other states require a supermajority legislative vote of either two-thirds or three-fourths.