In commerce freedom of contract shall prevail subject to the law. Usury is forbidden. Contracts contrary to public morality are null and void. ARTICLE 153. Property is guaranteed by the constitution. Its rights and responsibilities and restrictions are to be laid down by law. Expropriation can only be undertaken in the common interest and in virtue of a law. Adequate compensation shall be paid, unless otherwise provided by act of the Realm. Any dispute as to the amount of compensation shall be referred to the ordinary courts. Property of the Lands, the local authorities, or public associations can only be expropriated by the Realm against compensation. Property imposes obligations. Its use by the owner must at the same time serve the common good. ARTICLE 154. The right of inheritance shall be guaranteed in accordance with the Civil Code. The laws shall determine the proportion of inherited property accruing to the State. ARTICLE 155. Distribution and cultivation of the soil shall be supervised by the State so as to ensure against abuses and to endeavour to secure healthy housing for every German, and suitable homes for each German family, especially those with many children, in which they can live and work. In drawing up a housing code special consideration shall be paid to the claims of those who have fought in the war. Landed estate may be expropriated if it is required for housing, or for a settlement or reclamation policy, or in the interests of agriculture. Entails shall be abolished. The owner of the soil is bound to cultivate and make use of his land, in the common interest. Increment value due to no expenditure of work or of capital shall be utilised for the common good. All riches of the soil and all natural resources of economic use shall be under the supervision of the State. Private royalties shall, by law, be transferred to the State. ARTICLE 156. An act of the Realm may without prejudice to the payment of compensation, and subject to the regulations concerning expropriation, transfer to public ownership private businesses suitable for socialisation. It may name itself, the Lands, or Local Authority as partners in the administration of such business undertakings or associations, or in any other way assure itself a predominant influence therein. The Realm may further legislate, in case of urgent necessity and in the interest of the national economy, to oblige business undertakings or associations to combine, on the basis of self administration, with a view to securing the co-operation of all the productive forces of the nation, to associating employers and employed in the administration, and to regulating production, manufacture, distribution, employment, prices, as also import and export of goods on principles of public economy.