Issues in relation to which referendums are optional at the national level

Poland
- Constitutional amendments
- Adoption of international treaties
- Transfer of authority to international bodies
Art.90 p. 3, art. 125, art. 235 p. 6 of the Polish Constitution
Constitution of the Republic of Poland adopted on 2April 1997
http://www.sejm.gov.pl/prawo/konst/angielski/kon1.htm (in English - the Parliament’s website)
Constitutionalamendments – referendum can be called only if the constitutional amendmentrefers to the provisions of chapter I, II and XII of the Constitution
Adoptionof international treaties, Transfer of authority to international bodies – thesubject of the referendum is to express consent for the President to ratify international agreements, which delegate to aninternational organization or international institution the competence oforgans of State authority in relation to certain matters
Other- referendum may be held in respect of matters of particular importance to theState