Under the Oklahoma Constitution, citizens have the power to repeal legislation via veto referendum. Article V, Section 3 states:
Referendum petitions shall be filed with the Secretary of State not more than ninety (90) days after the final adjournment of the session of the Legislature which passed the bill on which the referendum is demanded. The veto power of the Governor shall not extend to measures voted on by the people. All elections on measures referred to the people of the state shall be had at the next election held throughout the state, except when the Legislature or the Governor shall order a special election for the express purpose of making such reference. Any measure referred to the people by the initiative or referendum shall take effect and be in force when it shall have been approved by a majority of the votes cast thereon and not otherwise.
To put a veto referendum on the ballot requires signatures equal to 5 percent of voters in the last Gubernatorial election. Currently (2019), a veto referendum would require 59,320 signatures to get on the ballot. After a veto referendum is drafted, it goes through a lengthy process which can include various legal challenges.
There have been 20 veto referendums in Oklahoma history, with the last one in 1970. An unsuccessful 1991 effort to repeal House Bill 1017 was conducted through a proposed constitutional amendment, not a veto referendum. In 2018, a veto referendum campaign (State Question 799) to overturn HB 1010xx, a revenue-raising measure that passed with 3/4 support from both chambers, was struck down by the Oklahoma Supreme Court. In August 2019, a veto referendum effort was launched to challenge HB 2597, which will allow for the permitless carry of firearms in Oklahoma.