Constitutional practicability of referendum on EU Constitution

Yes. Binding referendum provided if amendment of fundamental principles of constitution effected but Art. 6 EU Treaty guarantees integracy of these principles. Binding referendum also provided expressly for international treaties and subjects of particular importance for the state.

Approval of international treaties without any transfer of sovereignty

Majority from members of parliament and from senate, Art. 89 I, 120 ConstPoland. Requirements for approval can be regulated by law, Art. 89 III ConstPoland.

Approval of transfer of sovereignty without effect of constitutional amendment

Majority from both chambers with 2/3 of votes by presence of at least 1/2 of their members, Art. 90 II ConstPoland. Additionally, a referendum in accordance to Art. 125 ConstPoland can be called, Art. 90 III ConstPoland.

Approval of transfer of sovereignty with effect of constitutional amendment

Not expressly regulated but constitutional amendment required.

Approval of constitutional amendment

A bill submitted by at least 1/5 of the members of parliament, the senate or the President has to be approved with majority of 2/3 of votes from parliament by presence of at least 1/2 of its members and majority of the members of senate, Art. 235 IV ConstPoland. Amendment of fundamental principles of the constitution requires additionally a confirmatory referendum, Art. 235 VI ConstPoland.

Other constitutional regulations about referendums

Referendum on subjects of particular importance for the state initiated by the parliament with majority of its members or the President approved by the senate with majority of its members can be called and is binding if more than 1/2 of those having the right to vote have participated in it, Art. 125 ConstPoland. Any referendum has to be determined by the Supreme Court, Art. 125 IV ConstPoland.