The Regulation is binding upon the European Union Member States that participated in its adoption. In 2016, there were 25 of them.
States that become members of the European Union in the future will be bound by the text which is part of the Community acquis.
Three European Union Member States are not bound by the Regulation.
Denmark
United Kingdom and Ireland
In these three States, the Regulation and the solutions it contains do not apply unless they should serve notice at some time in the future of their intention to be bound by the Regulation.
Therefore, if the authorities of these States are seised with a succession that is connected with another Member State, they will apply their national rules of conflict.
On the other hand, if the authorities of one of the 25 Member States that are bound by the Regulation must settle a succession that is connected with one of these three States, they will apply the Regulation. The same remark applies to relationships with non-European Union third countries.
Several of the provisions of the Regulation, notably on the matter of renvois, use the notion of Member State.
The United Kingdom, Denmark and Ireland might be considered as being included in this notion.
This interpretation should be ruled out, however, as the Member States within the meaning of the Regulation are the Member States bound by the Regulation and not the European Union Member States.