Dutch nationality law details the conditions by which a person holds Dutch nationality. The primary law governing these requirements is the Dutch Nationality Act, which came into force on 1 January 1985. Regulations apply to the entire Kingdom of the Netherlands, which includes the country of the Netherlands itself, Aruba, Curaçao, and Sint Maarten. The Netherlands is a member state of the European Union (EU) and all Dutch nationals are EU citizens. They have automatic and permanent permission to live and work in any EU or European Free Trade Association (EFTA) country and may vote in elections to the European Parliament. Any person born to at least one Dutch parent receives Dutch citizenship at birth. Foreign nationals may naturalise as Dutch citizens after living in any part of the Kingdom for at least five years, demonstrating proficiency in the Dutch language, renouncing any previous nationalities, and fulfilling a good character requirement. Acquisition of citizenship By descent or automatic acquisition of Dutch nationality A person born on or after 1 January 1985 to a Dutch father or mother (afstamming) is automatically a Dutch national at birth (van rechtswege). It is irrelevant where the child is born. A child born to an unmarried Dutch father and a non-Dutch mother must be acknowledged by the Dutch father before birth, in order for the child to be a Dutch national at birth. Before 1 April 2003, an acknowledgement could be given after birth. Since then children who were not acknowledged before birth may nonetheless acquire Dutch citizenship through the option procedure, or through obtaining proof of paternity from a court. In the last case, the child gets Dutch nationality retroactively since the child's birth. From 1 January 1985 the Kingdom Act on the Netherlands nationality (Rijkswet op het Nederlanderschap 19 December 1984, Stb. 628) permits children of either a Dutch father or mother to receive Dutch nationality by descent. Prior to that date Dutch nationality law (Wet op het Nederlanderschap en het ingezetenenschap (commonly abbreviated as WNI, 12 December 1892, Stb. 268) did not permit children to obtain Dutch nationality through descent from a Dutch mother (through matrilineal descent) and a non-Dutch father. Netherlands nationality was only passed through patrilineal (father) descent. Only if the father was not known or acknowledged did a child born to a Dutch mother receive Dutch nationality prior to 1 January 1985. Between 1 January 1985 and 31 December