Executive Order No. 464 is unconstitutional in part: Sections 2(b) and 3 are void because they allow executive officials to evade congressional inquiries without a specific and properly invoked claim of executive privilege by the President or the Executive Secretary (by order of the President), thereby unduly infringing upon the legislative power of inquiry. Section 1 is valid when construed to apply only to the Question Hour (Art. VI, Sec. 22, Constitution), and Section 2(a) is valid as an internal guideline for the executive department concerning information that may be considered privileged.

The case arose from various Senate inquiries into matters of public concern, including the North Luzon Railways (NorthRail) Project, the "Gloriagate Scandal" involving alleged electoral fraud and wiretapping, and the fertilizer fund scam. Several executive officials invited to these hearings declined to attend, citing E.O. 464, which President Gloria Macapagal-Arroyo issued on September 28, 2005. This prompted multiple petitioners, including the Senate, legislators, and public interest groups, to challenge the constitutionality of E.O. 464 before the Supreme Court.

• The Senate of the Philippines, through various committees, conducted inquiries in aid of legislation on several issues: the NorthRail Project, the "Gloriagate Scandal," wiretapping activities, and the fertilizer fund scam.
• Invitations were issued to various executive officials to appear as resource persons in these hearings.
• On September 28, 2005, President Gloria Macapagal-Arroyo issued Executive Order No. 464, titled "Ensuring Observance of the Principle of Separation of Powers, Adherence to the Rule on Executive Privilege and Respect for the Rights of Public Officials Appearing in Legislative Inquiries in Aid of Legislation Under the Constitution, and For Other Purposes."
• Section 1 of E.O. 464 required all heads of departments of the Executive Branch to secure the consent of the President prior to appearing before either House of Congress.
• Section 2(a) defined the nature and scope of executive privilege, covering confidential or classified information between the President and public officials, military, diplomatic and national security matters, inter-government agency information prior to treaties, Cabinet meeting discussions, and matters affecting national security and public order.
• Section 2(b) enumerated officials covered by the executive order, including senior executive department officials, AFP generals and flag officers, senior PNP officers, senior national security officials (as determined by department heads, Chief of Staff, PNP Chief, or National Security Adviser respectively), and others determined by the President.
• Section 3 required all public officials enumerated in Section 2(b) to secure prior consent of the President before appearing before Congress to ensure observance of separation of powers, executive privilege, and rights of public officials.
• Following the issuance of E.O. 464, several executive officials, including Cabinet members and AFP officers, declined to attend scheduled Senate hearings, citing the new executive order and their inability to secure presidential consent.
• Brig. Gen. Gudani and Col. Balutan, who testified despite the order, were relieved from their posts and faced court-martial proceedings.
• Multiple petitions were filed challenging the constitutionality of E.O. 464, arguing it infringed on Congress's power of inquiry, the people's right to information, and other constitutional provisions.

• E.O. 464 is unconstitutional because it violates Congress's power of inquiry in aid of legislation (Article VI, Section 21 of the Constitution) by imposing a presidential gag on executive officials.
• E.O. 464 infringes upon the people's right to information on matters of public concern (Article III, Section 7 and Article II, Section 28 of the Constitution) by preventing the disclosure of information through congressional hearings.
• Section 1 of E.O. 464, requiring presidential consent for department heads, misinterprets Article VI, Section 22 (Question Hour) and unlawfully extends it to inquiries in aid of legislation.
• Sections 2(b) and 3 of E.O. 464 constitute an invalid and overly broad assertion of executive privilege, and improperly delegate to department heads the determination of who is covered by executive privilege and the power to invoke it.
• The implementation of E.O. 464 prior to its publication in the Official Gazette or a newspaper of general circulation violated due process.
• E.O. 464 unduly expands the scope of executive privilege beyond constitutionally recognized limits (e.g., state secrets, presidential communications).

• E.O. 464 is a valid exercise of presidential power, necessary to protect executive privilege and ensure the separation of powers.
• The President has the power to control and supervise the executive branch, including the appearance of its officials before Congress.
• Executive privilege is a recognized constitutional doctrine essential for the effective functioning of the executive branch.
• Petitioners lack legal standing, and there is no actual case or controversy ripe for judicial review as the President had not explicitly prohibited officials from attending, but merely required them to secure consent.
• E.O. 464 does not require publication as it is an internal directive to executive officials.
• The requirement of presidential consent is a reasonable measure to ensure that appearances are consistent with national security, public interest, and the rights of officials.

• Whether E.O. 464 contravenes the power of inquiry vested in Congress (Article VI, Section 21).
• Whether E.O. 464 violates the right of the people to information on matters of public concern (Article III, Section 7).
• Whether respondents committed grave abuse of discretion when they implemented E.O. 464 prior to its publication in a newspaper of general circulation.
• Whether Section 1 of E.O. 464, requiring presidential consent for department heads to appear before Congress, is constitutional.
• Whether Sections 2(b) and 3 of E.O. 464, requiring other executive officials to secure presidential consent and defining coverage of executive privilege, are constitutional.

• The petitions are PARTLY GRANTED. Sections 2(b) and 3 of E.O. 464 are declared VOID. Sections 1 and 2(a) are declared VALID, with qualifications.
• On Standing and Actual Case: The Court found that the Senate, its members, and other petitioners like legislators and citizen groups had legal standing. An actual case or controversy existed because the implementation of E.O. 464 had already resulted in the non-appearance of executive officials at congressional hearings.
• On Congress's Power of Inquiry (Art. VI, Sec. 21): Congress's power of inquiry is inherent in its legislative function and is essential for informed lawmaking. This power extends to compelling the attendance of executive officials, except the President, unless a valid claim of executive privilege is made.
• On Executive Privilege: Executive privilege is recognized and allows the President to withhold certain types of sensitive information. However, a claim of executive privilege must be specific, state the precise reasons for the claim, and be invoked by the President or the Executive Secretary by order of the President. It cannot be a blanket prohibition.
• Validity of Section 1 of E.O. 464: Section 1, requiring presidential consent for department heads, is valid only when applied to appearances during the Question Hour under Article VI, Section 22 of the Constitution, where attendance is discretionary. It is invalid if applied to inquiries in aid of legislation under Article VI, Section 21, where attendance is compulsory, unless executive privilege is validly invoked.
• Validity of Section 2(a) of E.O. 464: Section 2(a), enumerating types of information potentially covered by executive privilege, is valid as mere internal guidelines for the executive branch and is not conclusive on other branches of government.
• Invalidity of Sections 2(b) and 3 of E.O. 464: Section 2(b) (defining covered officials) and Section 3 (requiring presidential consent for these officials) are unconstitutional. They allow for an implied claim of executive privilege without specific grounds, effectively barring officials from appearing before Congress without a formal and justifiable assertion of privilege. They also improperly delegate the power to determine who is covered by executive privilege and to effectively invoke it by silence or non-action by the President. The power to invoke executive privilege is limited to the President or the Executive Secretary, by order of the President.
• On the Right to Information (Art. III, Sec. 7): E.O. 464, by unduly limiting disclosures in legislative investigations (which are generally public and presumed to be on matters of public concern), directly impairs the people's right to information.
• On Publication: E.O. 464, having a direct effect on the public's right to information and Congress's power of inquiry, is a matter of public interest and requires publication for its effectivity. Its implementation prior to publication was a violation of due process.

• Separation of Powers — The constitutional principle distributing governmental powers among the legislative, executive, and judicial branches, each co-equal and supreme within its own sphere. Applied in analyzing the distinct powers of Congress to inquire (Art. VI Sec. 21) versus the Question Hour (Art. VI Sec. 22), and the President's power to claim executive privilege versus Congress's need for information.
• Power of Inquiry (Legislative Inquiry) — The inherent power of Congress to conduct investigations in aid of legislation to gather information necessary for the intelligent enactment of laws. The Court affirmed this power is broad and compulsory, but subject to constitutional limitations like the rights of persons and executive privilege. E.O. 464 Sections 2(b) and 3 were found to unduly obstruct this power.
• Executive Privilege — The President's power to withhold certain information from the public, Congress, and the courts. The Court reiterated that this privilege is not absolute and must be invoked specifically by the President or the Executive Secretary (by order of the President), with stated reasons, and is limited to recognized categories like state secrets, presidential communications, and deliberative process. Sections 2(b) and 3 of E.O. 464 were voided for allowing an overly broad and improperly invoked assertion of this privilege.
• Question Hour (Art. VI, Sec. 22, Constitution) — A constitutional provision allowing heads of departments to appear before Congress to answer questions, upon their own initiative with presidential consent, or upon request of either House. Appearance is discretionary for department heads. Section 1 of E.O. 464 was upheld as valid only in this context.
• Right to Information on Matters of Public Concern (Art. III, Sec. 7, Constitution) — The right of the people to access official records and documents pertaining to official acts, transactions, or decisions, as well as government research data used for policy development. The Court held that E.O. 464's restrictions on congressional inquiries, which are generally public, also impaired this right.
• Locus Standi (Legal Standing) — The requirement that a party bringing a lawsuit must have a personal and substantial interest in the case, such that they have sustained or will sustain direct injury as a result of the governmental act being challenged. The Court found that the Senate, legislators, and citizen groups had standing to challenge E.O. 464.
• Actual Case or Controversy — A requirement for judicial review that there must be a genuine dispute involving legally demandable and enforceable rights. The Court found this requisite met due to the actual non-appearance of officials at Senate hearings citing E.O. 464.
• Requirement of Publication (Tañada v. Tuvera doctrine) — Laws and issuances of public interest or general applicability must be published in the Official Gazette or a newspaper of general circulation to be effective, as part of due process. The Court ruled E.O. 464, affecting public rights and congressional powers, required publication.
• Presumption of Constitutionality — Legislative and executive issuances are presumed constitutional until proven otherwise. The Court acknowledged this but found parts of E.O. 464 violative of the Constitution.
• Ejusdem Generis — A rule of statutory construction where general words following an enumeration of specific classes of persons or things are construed as applying only to persons or things of the same general kind or class as those specifically mentioned. Applied in interpreting Section 2(b) of E.O. 464 regarding "such other officers as may be determined by the President."

• "The power of inquiry - with process to enforce it - is an essential and appropriate auxiliary to the legislative function." (Quoting Arnault v. Nazareno)
• "Executive privilege, whether asserted against Congress, the courts, or the public, is recognized only in relation to certain types of information of a sensitive character. Noticeably absent is any recognition that executive officials are exempt from the duty to disclose information by the mere fact of being executive officials. Indeed, the extraordinary character of the exemptions indicates that the presumption inclines heavily against executive secrecy and in favor of disclosure."
• "When Congress exercises its power of inquiry, the only way for department heads to exempt themselves therefrom is by a valid claim of privilege. They are not exempt by the mere fact that they are department heads."
• "A claim of privilege, being a claim of exemption from an obligation to disclose information, must, therefore, be clearly asserted."
• "To deny the Committee the opportunity to consider the objection or remedy is in itself a contempt of its authority and an obstruction of its processes." (Quoting McPhaul v. U.S.)
• "[W]hat republican theory did accomplish-was to reverse the old presumption in favor of secrecy, based on the divine right of kings and nobles, and replace it with a presumption in favor of publicity, based on the doctrine of popular sovereignty."

• Arnault v. Nazareno — Referenced for establishing the inherent power of Congress to conduct inquiries in aid of legislation and to compel testimony, and that this power is co-extensive with the power to legislate.
• Almonte v. Vasquez — Cited for recognizing executive privilege in Philippine jurisprudence, particularly concerning presidential conversations and correspondences, rooted in the separation of powers and the need for candid advice in decision-making.
• Chavez v. PCGG — Referenced for acknowledging governmental privilege against public disclosure for state secrets (military, diplomatic, national security) and that closed-door Cabinet meetings are a limitation on the right to information.
• Chavez v. Public Estates Authority (PEA) — Cited for the principle that the right to information does not extend to privileged information under the separation of powers (presidential conversations, Cabinet meetings, military/diplomatic secrets, national security matters). Also, used to illustrate that an implied claim of privilege (as authorized by E.O. 464) is insufficient.
• Bengzon v. Senate Blue Ribbon Committee — Mentioned for the principle that a legislative inquiry must be in aid of legislation and not usurp judicial functions.
• U.S. v. Nixon — The leading U.S. case on executive privilege, cited for its constitutional basis but also for the requirement that the privilege must be balanced against other compelling public interests (e.g., administration of criminal justice).
• Tañada v. Tuvera — Referenced for the doctrine that all laws and issuances of public interest must be published for effectivity. E.O. 464 was deemed to require publication.
• U.S. v. Reynolds — Cited for the requirement that a claim of executive privilege must be formally lodged by the head of the department after personal consideration, and not lightly invoked.
• McPhaul v. U.S. — Cited to emphasize that reasons for non-compliance with a congressional subpoena (or claim of privilege) must be stated to Congress, and failure to do so can be contemptuous.

• Constitution, Art. VI, Sec. 21 (Power of Inquiry) — Central to the case, as E.O. 464 was seen to primarily restrict this congressional power. The Court held that attendance of executive officials is compulsory under this section, unless executive privilege is validly invoked.
• Constitution, Art. VI, Sec. 22 (Question Hour) — The Court ruled that Section 1 of E.O. 464 is valid only in the context of this provision, where the appearance of department heads is discretionary and requires presidential consent.
• Constitution, Art. III, Sec. 7 (Right to Information) — E.O. 464 was found to impair this right by limiting disclosures in legislative investigations, which are generally public and concern matters of public interest.
• Constitution, Art. II, Sec. 28 (Full Public Disclosure) — Complements the right to information, underscoring the policy of transparency allegedly undermined by E.O. 464.
• Constitution, Art. XI, Sec. 1 (Public Office is a Public Trust) — Invoked by petitioners to argue for accountability, which E.O. 464 allegedly subverted.
• Republic Act No. 6713 (Code of Conduct and Ethical Standards for Public Officials and Employees) — Mentioned in E.O. 464 itself regarding the non-disclosure of confidential information, but the Court's ruling focused on the constitutional power of inquiry.