To ask Her Majesty’s Government which EU countries are required by their constitutions to hold a referendum before their governments can agree changes to the EU treaties; and which countries have done so in the past.

No EU country has an absolute constitutional requirement to hold a referendum before their government can agree to any amendment to the EU Treaties. Indeed, no EU Member State held a referendum on the most recent change to the EU Treaties which came into effect in 2013.

The following countries have a constitutional requirement to hold a referendum in certain circumstances (e.g. if proposed changes require a revision of a Member State’s constitution or constitute a transfer of competence/sovereignty to the EU):

• Austria

• Croatia

• Denmark

• Ireland

• Lithuania

• Romania

• Slovakia

The following countries have previously held a referendum on changes to the EU Treaties:

• Denmark

• Ireland

• France

• Italy

• Luxembourg

• Netherlands

• Spain