Oregon Constitution Art. II § 23

(1) Any measure that includes any proposed requirement for more than a majority of votes cast by the electorate to approve any change in law or government action shall become effective only if approved by at least the same percentage of voters specified in the proposed voting requirement.

(2) For the purposes of this section, “measure” includes all initiatives and all measures referred to the voters by the Legislative Assembly.

(3) The requirements of this section apply to all measures presented to the voters at the November 3, 1998 election and thereafter.

(4) The purpose of this section is to prevent greater-than-majority voting requirements from being imposed by only a majority of the voters.