On and from the appointed day, the common High Court shall have, in respect of the territories comprised in the States of Assam, Manipur, Meghalaya, Nagaland and Tripura, all such jurisdiction, powers and authority as under the law in force immediately before the appointed day, are exercisable in respect of those territories by the High Court of Assam and Nagaland or the Court of the Judicial Commissioner for Manipur, or the Court of the Judicial Commissioner for Tripura, as the case may be.