Statute law referendum is a constitutionally-defined, citizen-initiated, petition process of the "proposed veto of all or part of a legislature-made law," which, if successful, repeals the standing law. It is used at the state level in twenty-four states: Alaska, Arizona, Arkansas, California, Colorado, Idaho,
Kentucky, Maine,
Maryland, Massachusetts, Michigan, Missouri, Montana, Nebraska, Nevada,
New Mexico, North Dakota, Ohio, Oklahoma, Oregon, South Dakota, Utah, Washington and Wyoming (Cronin, 1989). There are now a total of 24 U.S. states with constitutionally-defined, citizen-initiated, direct democracy governance components (Zimmerman, December 1999). In the United States, for the most part only one-time majorities are required (simple majority of those voting) to approve any of these components.
http://en.wikipedia.org/wiki/Direct_democracy#Direct_democracy_in_the_United_States