" Clauses (2) and (6) of Article 31 which are relevant for these cases as they stood at the commencement of the Constitution read as follows: "31. (1) (2) No property, moveable or immovable, including any interest in, or in any company owning, any commercial or industrial undertaking, shall be taken possession of or 532 acquired for public purposes under any law authorising the taking of such possession or such acquisition, unless the law provides for compensation for the property taken possession of or acquired and either fixes the amount of the compensation, or specifies the principles on which, and the manner in which, the compensation is to be determined and given. . . . . . (6) Any law of the State enacted not more than eighteen months before the commencement of this Constitution may within three months from such commencement be submitted to the President for his certification; and thereupon, if the President by public notification so certifies, it shall not be called in question in any court on the ground that it contravenes the provisions of clause (2) of this article or has contravened the provisions of sub section (2) of section 299 of the Government of India Act, 1935.