Tinio, et al. vs. Duterte, et al.

The presumption of constitutionality and regularity accorded to a statute, as an official act of a co-equal branch, prevails absent clear and convincing evidence of a constitutional violation. The Court will not inquire into the internal proceedings of Congress, such as the determination of a quorum during a session, as this is governed by its own rules and is conclusively shown by its official Journal and the enrolled bill. Furthermore, the legislature's plenary power to tax includes the discretion to impose excise taxes, and such measures are not per se unconstitutional for being regressive or for incidentally affecting the poor, provided they are not confiscatory and are accompanied by social mitigating measures.

Republic Act No. 10963, or the Tax Reform for Acceleration and Inclusion (TRAIN) Act, was the first package of the Comprehensive Tax Reform Program. It amended the National Internal Revenue Code to adjust income tax rates and increase excise taxes on various products, including diesel, kerosene, liquefied petroleum gas (LPG), and coal. The law was certified as urgent by the President and was intended to fund infrastructure and social programs. Two sets of petitions were filed directly with the Supreme Court, challenging the law's validity on both procedural and substantive grounds.

• Nature of the Action: Two consolidated petitions for certiorari and prohibition sought to declare Republic Act No. 10963 (TRAIN Act) unconstitutional and to enjoin its implementation.
• The Legislative Process: The precursor bills (HB No. 5636 and SB No. 1592) were certified as urgent. The Bicameral Conference Committee (BCC) Report was ratified by the House of Representatives on the night of December 13, 2017. The session had commenced at 4:00 p.m. with a roll call showing 232 of 295 members present, establishing a quorum. The session was suspended and resumed at 10:02 p.m., after which the BCC Report was ratified "without objection." The session adjourned at 10:05 p.m.
• Petitioners' Allegations (Tinio et al.): The ratification was "railroaded" because there was no quorum at the time of the vote, as evidenced by a video recording and a photograph of a near-empty session hall. This violated Section 16(2), Article VI of the Constitution. Consequently, the President's signing of the law was tainted with grave abuse of discretion.
• Petitioners' Allegations (Laban Konsyumer): The excise tax on coal was a "rider" not originating from the House, violating Section 24, Article VI. The excise taxes on diesel, coal, LPG, and kerosene are regressive, confiscatory, and violate the due process and equal protection clauses, as they disproportionately burden the poor.
• Respondents' Defense (OSG): The petitions were procedurally infirm (improper remedy, violation of hierarchy of courts, no actual controversy, political question, failure to implead indispensable parties, violation of presidential immunity). On the merits, the House Journal conclusively showed a quorum, the enrolled bill doctrine applied, the Senate's amendments were valid, and the law's social mitigating measures (e.g., unconditional cash transfers) cushion its impact, making it neither confiscatory nor unconstitutionally discriminatory.

• Invalid Enactment / Lack of Quorum: Petitioners argued that the House lacked a quorum when it ratified the BCC Report, rendering the entire enactment process void. They submitted a video and photograph as evidence contradicting the Journal's entries.
• Rider / Origin of Revenue Bill: The provision imposing excise tax on coal (amending Section 151 of the Tax Code) was not in the House bill and was a prohibited rider, violating the constitutional requirement that revenue bills must originate exclusively from the House.
• Due Process Violation: The excise taxes on petroleum products and coal are arbitrary, unreasonable, and confiscatory. They operate as taxes on subsistence, directly increasing the cost of basic necessities and depriving low-income families of property without due process.
• Equal Protection & Progressive Taxation Violation: The taxes expressly discriminate against the poor while favoring the rich, as the affected commodities are essential for the poor. The law is regressive, violating the constitutional mandate for Congress to "evolve a progressive system of taxation."

• Procedural Infirmities: Certiorari was improper; the petitions violated the hierarchy of courts; there was no actual case or controversy; the issues were political questions; Congress was an indispensable party not impleaded (in G.R. No. 236118); and the President was immune from suit.
• Valid Enactment & Conclusiveness of Journal: The House Journal (No. 48) is a constitutional record that is binding and conclusive. It explicitly stated a quorum was present at the start of the session, and no valid point of order questioning quorum was raised during the ratification. The enrolled bill, signed by congressional leaders and the President, is conclusive proof of due enactment.
• Senate's Amendatory Power: Section 24, Article VI only requires that revenue bills originate in the House. It does not limit the Senate's power to propose amendments, even extensive ones. The coal tax amendment was germane to the bill's purpose of raising revenue.
• Constitutionality of Tax Provisions: The taxes are imbued with valid policy considerations (revenue generation, regulatory purposes). The law is not confiscatory because it includes social mitigating measures (cash transfers, fuel vouchers, discounts) to protect vulnerable sectors. The regressivity of an indirect tax is not a ground for unconstitutionality; the constitutional directive is for Congress to evolve a progressive system, not to prohibit all regressive taxes.

• Jurisdiction & Justiciability: Whether the Court may take cognizance of the petitions under its expanded judicial power, given the allegations of grave abuse of discretion by a co-equal branch.
• Hierarchy of Courts: Whether direct resort to the Supreme Court is justified despite the doctrine of hierarchy of courts.
• Indispensable Party: Whether Congress, as an institution, is an indispensable party that should have been impleaded.
• Presidential Immunity: Whether the inclusion of the President as a respondent violates the doctrine of presidential immunity from suit.
• Validity of Enactment: Whether the TRAIN Act was invalidly enacted due to an alleged lack of quorum in the House during the ratification of the Bicameral Conference Committee Report.
• Rider: Whether the provision amending Section 151 of the Tax Code (imposing excise tax on coal) is an unconstitutional rider.
• Due Process: Whether the excise taxes on diesel, coal, LPG, and kerosene are confiscatory and violate the due process clause.
• Equal Protection & Progressive Taxation: Whether the same taxes violate the equal protection clause and the constitutional mandate for a progressive system of taxation.

• Jurisdiction & Justiciability: The petitions presented an actual case or controversy, petitioners had locus standi, and the issues were the lis mota. The Court's expanded judicial power allows it to determine whether any branch committed grave abuse of discretion. The political question doctrine does not bar review.
• Hierarchy of Courts: Direct resort was justified. The cases involved genuine issues of constitutionality of transcendental importance, requiring immediate resolution by the highest court.
• Indispensable Party: The requirement was substantially complied with. In G.R. No. 236295, the House and Senate were impleaded through their respective heads in their official capacities. Since the cases were consolidated, this sufficed.
• Presidential Immunity: The inclusion of the President as a respondent violated the doctrine of presidential immunity from suit, which makes no distinction between official and unofficial acts. The President was ordered dropped as a party.
• Validity of Enactment: The TRAIN Act was validly enacted. The determination of a quorum during an ongoing session is an internal matter within the exclusive control of the House, governed by its own rules. The House Journal No. 48 conclusively established the presence of a quorum at the session's start. The enrolled bill doctrine further confirmed the law's due enactment. Petitioners' video and photographic evidence were insufficient to overcome the presumption of regularity and the conclusiveness of the Journal.
• Rider: The coal tax provision was not a prohibited rider. The Constitution only requires that revenue bills originate in the House; it does not limit the Senate's power to propose amendments. The amendment was germane to the bill's purpose of raising revenue.
• Due Process: The taxes are not confiscatory. The power to tax is plenary, and its exercise is presumed valid. Petitioners failed to provide clear and convincing evidence that the taxes amount to a deprivation of property. The law must be read as a whole, including its social mitigating measures (e.g., unconditional cash transfers, fuel vouchers, discounts) designed to cushion the impact on the poor.
• Equal Protection & Progressive Taxation: The taxes do not violate equal protection. There is no express discriminatory classification; the law's effects are incidental. The constitutional directive in Section 28(1), Article VI for Congress to "evolve a progressive system of taxation" is a moral incentive to legislation, not a judicially enforceable right that prohibits regressive taxes. The regressivity of an excise tax is not, by itself, a ground for invalidation.

• Enrolled Bill Doctrine — A statute signed by the presiding officers of both Houses of Congress and certified by their respective Secretaries, and approved by the President, is conclusive proof of its due enactment. The Court will not look beyond the four corners of the enrolled bill absent extraordinary circumstances (e.g., a clear showing of unconstitutionality or a withdrawal of authentication).
• Conclusiveness of the Legislative Journal — The Journal of each House of Congress, as a constitutional record, is binding and unimpeachable. Its entries on the presence of a quorum and the conduct of proceedings are presumed true and regular.
• Separation of Powers & Internal Legislative Proceedings — The judiciary cannot inquire into the internal proceedings of Congress, such as the determination of a quorum during a session, as this is governed by its own rules and constitutes an impermissible interference in the domain of a co-equal branch.
• Presidential Immunity from Suit — The President may not be sued during his or her tenure. This privilege is absolute and does not distinguish between official and unofficial acts.
• Plenary Power of Taxation & Presumption of Constitutionality — The legislature's power to tax is comprehensive and subject to wide discretion. Tax laws enjoy a strong presumption of constitutionality, which can only be overcome by a clear and unequivocal breach of the Constitution.
• Regressivity Not a Judicially Enforceable Standard — The constitutional mandate for Congress to "evolve a progressive system of taxation" (Article VI, Section 28(1)) is not a negative standard that prohibits the imposition of regressive taxes like excise taxes. It is a directive to the legislature, not a judicially enforceable right.

• "The respect due to coequal and independent departments requires the [Judiciary] to act upon that assurance, and to accept, as having passed Congress, all bills authenticated in the manner stated; leaving the court to determine, when the question properly arises, whether the Act, so authenticated, is in conformity with the Constitution." (On the enrolled bill doctrine, citing Council of Teachers and Staff of Colleges and Universities of the Philippines v. Secretary of Education)
• "Long, long centuries ago, these considerations of public policy led to the adoption of the rule giving verity and unimpeachability to legislative records. If that character is to be taken away for one purpose, it must be taken for all, and the evidence of the laws of the state must rest upon a foundation less certain and durable than that afforded by the law to many contracts between private individuals concerning comparatively trifling matters." (On the conclusiveness of the Journal, citing United States v. Pons)
• "The Constitution does not really prohibit the imposition of indirect taxes which, like the VAT, are regressive. What it simply provides is that Congress shall 'evolve a progressive system of taxation.' ... The constitutional provision has been interpreted to mean simply that 'direct taxes are ... to be preferred [and] as much as possible, indirect taxes should be minimized.' ... The mandate to Congress is not to prescribe, but to evolve, a progressive tax system." (On regressivity, citing Tolentino v. Secretary of Finance)
• "Let us likewise disabuse our minds from the notion that the judiciary is the repository of remedies for all political or social ills; We should not forget that the Constitution has judiciously allocated the powers of government to three distinct and separate compartments... judicial interpretation has tended to the preservation of the independence of the three, and a zealous regard of the prerogatives of each, knowing full well that one is not the guardian of the others..." (On judicial restraint, citing Abakada Guro Party List v. Hon. Exec. Sec. Ermita)

• Tolentino v. Secretary of Finance, 305 Phil. 686 (1994) — Controlling precedent. Established that Section 24, Article VI only requires revenue bills to originate in the House, but the Senate may propose extensive amendments. Also held that the mandate to evolve a progressive system of taxation does not prohibit regressive taxes like the VAT.
• Abakada Guro Party List v. Hon. Exec. Sec. Ermita, 506 Phil. 1 (2005) — Followed. Upheld the Senate's power to introduce amendments to a House revenue bill and discussed the nature of regressive taxes and the presumption of constitutionality of tax laws.
• Arroyo v. De Venecia, 343 Phil. 42 (1997) — Applied. Held that courts cannot declare a statute void for non-compliance with the internal rules of the legislature, as these are merely procedural and within the legislature's exclusive control.
• United States v. Pons, 34 Phil. 729 (1916) — Applied. Established the unimpeachability and conclusive verity of legislative journals as a matter of public policy.
• Council of Teachers and Staff of Colleges and Universities of the Philippines v. Secretary of Education, 841 Phil. 724 (2018) — Applied. Reaffirmed the enrolled bill doctrine and its rationale.
• Belgica v. Ochoa, 721 Phil. 416 (2013) — Distinguished. While it struck down the PDAF for violating separation of powers, the Court here emphasized that the internal determination of quorum is a different matter within Congress's exclusive domain.
• De Lima v. President Duterte, 865 Phil. 578 (2019) — Applied. Reiterated that presidential immunity from suit is absolute and does not distinguish between official and unofficial acts.

• Section 16(2), Article VI, 1987 Constitution — Provides that a majority of each House shall constitute a quorum to do business. The Court ruled that the determination of a quorum during a session is an internal matter for the House, and its Journal is conclusive on the matter.
• Section 24, Article VI, 1987 Constitution — Requires that all revenue or tariff bills must originate exclusively in the House of Representatives, but the Senate may propose or concur with amendments. The Court held this does not limit the Senate's amendatory power.
• Section 28(1), Article VI, 1987 Constitution — Mandates that the rule of taxation shall be uniform and equitable and that Congress shall evolve a progressive system of taxation. The Court ruled this is not a judicially enforceable prohibition against regressive taxes.
• Section 1, Article III, 1987 Constitution — The due process clause. The Court held the TRAIN Act's taxes are not confiscatory, especially in light of the law's social mitigating measures.
• Section 1, Article III, 1987 Constitution — The equal protection clause. The Court found no invidious discrimination, as the law's classifications are reasonable and its effects are addressed by safeguards.

Chief Justice Alexander G. Gesmundo (with a separate concurring opinion), and Justices Alfredo Benjamin S. Caguioa (dissenting), Henri Jean Paul B. Inting, Ramon Paul L. Hernando, Rodil V. Zalameda, Mario V. Lopez, Jhosep Y. Lopez, Jose Midas P. Marquez, Antonio T. Kho, Jr., and Maria Filomena D. Singh. Justice Amy C. Lazaro-Javier and Justice Samuel H. Gaerlan concurred. Justice Marvic M.V.F. Leonen filed a separate opinion. Justice Rosmari D. Carandang was on official leave.

• Justice Alfredo Benjamin S. Caguioa — In his dissent, Justice Caguioa argued that the House Journal itself, when read carefully, showed that no vote was taken on the ratification of the BCC Report, as required by the rules. The Journal entry stating "there being no objection" did not constitute a valid ratification by a majority vote. He would have declared the TRAIN Act invalidly enacted.