Section 1. The judicial power shall be vested in one Supreme Court and in such lower courts as may be established by law. Judicial power includes the duty of the courts of justice to settle actual controversies involving rights which are legally demandable and enforceable, and to determine whether or not there has been a grave abuse of discretion amounting to lack or excess of jurisdiction on the part of any branch or instrumentality of the Government. Section 2. The Congress shall have the power to define, prescribe, and apportion the jurisdiction of the various courts but may not deprive the Supreme Court of its jurisdiction over cases enumerated in Section 5 hereof. No law shall be passed reorganizing the Judiciary when it undermines the security of tenure of its Members. Section 3. The Judiciary shall enjoy fiscal autonomy. Appropriations for the Judiciary may not be reduced by the legislature below the amount appropriated for the previous year and, after approval, shall be automatically and regularly released. Section 4. (1) The Supreme Court shall be composed of a Chief Justice and fourteen Associate Justices. It may sit en banc or in its discretion, in division of three, five, or seven Members. Any vacancy shall be filled within ninety days from the occurrence thereof. (2) All cases involving the constitutionality of a treaty, international or executive agreement, or law, which shall be heard by the Supreme Court en banc, and all other cases which under the Rules of Court are required to be heard en banc, including those involving the constitutionality, application, or operation of presidential decrees, proclamations, orders, instructions, ordinances, and other regulations, shall be decided with the concurrence of a majority of the Members who actually took part in the deliberations on the issues in the case and voted thereon. (3) Cases or matters heard by a division shall be decided or resolved with the concurrence of a majority of the Members who actually took part in the deliberations on the issues in the case and voted thereon, and in no case without the concurrence of at least three of such Members. When the required number is not obtained, the case shall be decided en banc: Provided, that no doctrine or principle of law laid down by the court in a decision rendered en banc or in division may be modified or reversed except by the court sitting en banc. Section 5. The Supreme Court shall have the following powers: 1) Exercise original jurisdiction over cases affecting ambassadors, other public ministers and consuls, and over petitions for certiorari, prohibition, mandamus, quo warranto, and habeas corpus. (2) Review, revise, reverse, modify, or affirm on appeal or certiorari, as the law or the Rules of Court may provide, final judgments and orders of lower courts in: