The Attorney General, appearing for the appellant, rightly conceded that inasmuch as article 31(2) made the existence of a public purpose a necessary condition of acquisition the existence of such a purpose as a fact must be established objectively and the provision in section 8 relating to the conclusiveness of the declaration of Government as to the nature of the purpose of the acquisition must be held unconstitutional but he contended that the provision was saved by article 31(5)of the Constitution which provides: "Nothing in clause (2) shall affect (a) the provisions of any existing _ law other than a law to which the provisions of clause (6) apply, or. . . " Clause (6) reads thus: "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 public notification so certifies, it shall not be called question in any court on the ground that it contract the provisions of clause (2) of this article, 562.