Bunreacht na hÉireann – the Constitution of Ireland – outlines the basic law of the country.

To change the Constitution a referendum must he held with the people of Ireland having their opportunity to oppose or support changing the Constitution.

To vote in a referendum people must be citizens of the country and be 18 years of age.

The Constitution came into effect on the 29^th of December 1937 after being passed in July of that year. It replaced the Constitution of the Irish Free State, Saorstát Éireann, that came into being after the Civil War in 1922.