Unconstitutionality of Laws, Treaties, Executive or Administrative Orders
The declare a law or a treaty unconstitutional, according to Sec. 4(2), Art. VIII of the constitution:
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.
Cases or matters heard by 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. [Sec. 4 (3), Art. VIII]
The Supreme Court shall have the following powers: Review, revise, reverse, modify, or affirm on appeal or certiorari as the law of the Rules of Court may provide, final judgments or orders of lower courts in: All cases in which the constitutionality or validity of any treaty, international or executive agreement, law, presidential decree, proclamation, order, instruction, ordinance, or regulation in in question. [Sec. 5 (2-a), Art. VIII]