The principle: Article 4
By the terms of recitals 23[1] and 24[2], Court jurisdiction and legislative competence coincide: the court having jurisdiction in any dispute relating to a succession is that of the Member State in which the deceased had his habitual residenceat the time of his death.
Example :
Charlotte, an Austrian national, has lived in Toledo in Spain for 30 years. She died on 1st September 2015 during a holiday in France. A dispute arises between her three children, who are Austrian residents, as to how to share out her estate. A Spanish court will have jurisdiction.