(4) In order to exclude export premiums or to safeguard important social interests. ARTICLE 12. As long as, and in so far as, the Realm makes no use of its rights of legislation, the Lands retain the right of legislating. This does not apply to legislation which belongs to the Realm exclusively. The Government of the Realm has the right of veto against any legislation of the Lands which affects the provisions of Number 13 of Article 7, in so far as the interests of the whole community of the Realm are thereby affected. ARTICLE 13. Law of the Realm prevails against law of the Lands. Should any doubt or difficulty arise as to whether an act of the Land legislature is compatible with the law of the Realm, the competent authorities of the Realm or Land may appeal to the decision of a Supreme National Court of Judicature; as may be subsequently determined by an act of the Realm. ARTICLE 14. Acts of the Realm are administered by authorities of the Lands except in so far as may be otherwise determined by acts of the Realm. ARTICLE 15. The Government of the Realm has the right of supervision over those matters in which it has the right of legislation. The Government of the Realm may lay down general directions where acts of the Realm are administered by the authorities of the Lands. It may send commissioners to the authorities of the Lands, and with their concurrence to subordinate authorities in order to supervise the execution of the acts of the Realm. The Land Governments are bound to remedy, on demand of the Government of the Realm, any deficiencies which may have appeared in the course of executing the acts of the Realm. In cases of dispute, both National Government of the Realm and Governments of the Lands may appeal to the decision of a Supreme Court of Judicature, except where an act of the Realm declares another court to be competent. ARTICLE 16. Officials directly charged with administrative affairs of the Realm in any Land shall, as a rule, be citizens of that Land. Officials, employees, and workers in the employ of the Realm shall, if they so desire, be employed within their home Land, in so far as this is possible, and in so far as the requirements of the service or of their training are not prejudiced. ARTICLE 17. Every Land must have a liberal constitution.[14] The Representative Body must be elected by universal, equal, direct, and secret suffrage by all nationals of either sex, on the system of proportional representation.[15] The Government of the Lands must have the confidence of the Representative Body.[16] The principles laid down for the election of the Representative Body apply also to the elections to Local Bodies. Nevertheless, Land legislation may require, as an elector's qualification, domicile within the locality not exceeding one year.[17] ARTICLE 18.[18]