Germany
(art. 23 and 79 of the Basic Law of 1949). Parliamentary ratification by 2/3 majority in each federal chamber (Bundestag and Bundesrat).

Austria
(art. 50 of the Constitution of 1983). Parliamentary ratification by 2/3 majority in each chamber.

Belgium
(art. 53, 77 and 167 of the Constitution of 1994). Parliamentary ratification by absolute majority in both chambers in the absence of a constitutional amendment, or by 2/3 majority in each chamber (with a quorum of 2/3 members present) in the event of a constitutional amendment.

Bulgaria
(art. 85 of the Constitution of 1991) Parliamentary ratification by absolute majority.

Cyprus
(art. 50 of the Constitution of 1960). Parliamentary ratification by absolute majority. The president and the Council of Ministers can, however, veto parliament's decision.

Denmark
(art. 20 al. 1 and 2 of the Constitution of 1992). Parliamentary ratification by simple majority in the absence of a transfer of sovereignty, by 5/6 majority in the event of a transfer of sovereignty. In the latter case, if the parliamentary majority is less than 5/6 but more than half, the ratification proceeds by referendum.

Spain
(art. 94 of the Constitution of 1992). Parliamentary ratification by simple majority of parliament. The referendum procedure is purely advisory.

Estonia
(art. 121 of the Constitution of 1992). Parliamentary ratification by simple majority.

Finland
(art. 33 and 69 of the Constitution Act of 1995 revised in 2000). Parliamentary ratification by simple majority in the absence of a transfer of sovereignty, by 2/3 majority in the event of a transfer of sovereignty.

France
(art. 89 of the Constitution of 1958). Parliamentary ratification by simple majority in both chambers in the absence of a constitutional amendment, by referendum in the event of a constitutional amendement (except if the president asks for ratification by 3/5 majority of the joint chambers of parliament in Congress).

Greece
(art. 28 al. 2, 36 al. 2, 44 al. 2 of the Constitution of 1986). Parliamentary ratification by simple majority in the absence of a transfer of sovereignty, by 3/5 majority in the event of a transfer of sovereignty. Ratification by referendum at the discretion of the government or on "national questions of crucial importance".

Hungary
(art. 2 and 28 of the Constitution of 1949). Parliamentary ratification by 2/3 majority of parliament (with a quorum of ½ of MPs present).

Ireland
(art. 29 and 46 of the Constitution of 1990). Parliamentary ratification by simple majority in the absence of a transfer of sovereignty, by referendum in the event of a transfer of sovereignty.

Italy
(art. 72 and 75 of the Constitution of 2001). Parliamentary ratification by simple majority in each chamber.

Latvia
(art. 68 of the Constitution of 1992 revised in 2003). Parliamentary ratification by simple majority of parliament. Ratification by referendum in the event of "substantial changes in the terms of Latvia's accession to the European Union" and if demanded by half of its members of parliament.

Lithuania
(art. 138 of the Constitution of 1992). Parliamentary ratification by simple majority.

Luxemburg
(art. 37 and 114 of the Constitution of 1868). Parliamentary ratification by 2/3 majority in the absence of a transfer of sovereignty, by 2/3 majority with a quorum of ¾ members present in the event of a transfer of sovereignty. The referendum procedure is purely advisory.

Malta
(art. 71 of the Constitution of 1964). Parliamentary ratification by simple majority in principle, but the procedure varies depending on the constitutional amendments required.

Netherlands
(art. 91 of the Constitution of 1983). Ratification is at the discretion of parliament. In principle, it is solely parliamentary, by simple majority in the absence of a constitutional amendment, by 2/3 majority in both chambers in the event of an amendment to the Constitution.

Poland
(art. 89 and 90 of the Constitution of 1997). Parliamentary ratification by simple majority in each chamber in the absence of a transfer of sovereignty, by 2/3 majority in each of the two chambers with a quorum of half of the members present in the event of a transfer of sovereignty.

Portugal
(art. 115 and 161 of the Constitution). Parliamentary ratification by simple majority of parliament votes. Ratification by referendum at the discretion of the government and president on "significant questions of national interest".

Czech Republic
(art. 39 and 49 of the Constitution of 1992). Parliamentary ratification by simple majority in each chamber in the absence of a transfer of sovereignty, by 2/3 majority in each of the two chambers in the event of a transfer of sovereignty.

Romania
(art. 91 of the Constitution of 1991). Parliamentary ratification by simple majority in the 60 days following the signature of the treaty by the president.

United Kingdom
(no formal or written Constitution). Customary parliamentary ratification in each of the two chambers.

Slovakia
(art. 84 and 102 of the Constitution of 1992). Presidential ratification in principle. The president may call for parliamentary ratification by simple majority in the absence of a constitutional amendment or 3/5 majority in the event of a constitutional amendment.

Slovenia
(art. 3 of the Constitution of 1991 revised in 2003). Parliamentary ratification by 2/3 majority. Ratification by referendum if the National Assembly wishes – the result of the referendum is binding.

Sweden
(chapter 10 of the Constitution of 1989). Parliamentary ratification by simple, 3/4, or 5/6 majority depending on the extent of the transfer of sovereignty.