Issues excluded from being the subject of referendums at the national level
Finland
THE FINNISH CONSTITUTION
(Adopted1999; last amended 2011)
http://www.finlex.fi/fi/laki/kaannokset/1999/en19990731.pdf
Section 53 ? Referendum and citizens? initiative (new title, 1112/2011,entry into force 1.3.2012)
The decision to organise a consultative referendum is made by an Act,which shall contain provisions on the time of the referendum and on the choicesto be presented to the voters.
No issues are explicitly excluded from being the subject of national referendums.