Issues that can be proposed by citizens using the initiative process at the national level

Spanish Constitution 1978 Section 87

Legislative initiative belongs to Government, Congress of Deputies and Senate, in accordance with the Constitution and the Standing Orders of the Houses. An organic act shall lay down the manner and the requirements of the popular initiative for submission of non-governmental bills. In any case, no less than 500.000 authenticated signatures shall be required. This initiative shall not be allowed on matters concerning organic acts, taxation, international affairs or the prerogative of mercy.