Legislative power, while plenary, is not absolute. It is confined by explicit constitutional restrictions and inherent principles essential to the democratic framework. Mastery of these limitations is critical for Bar essays, as examiners frequently test examinees' ability to distinguish valid from invalid exercises of congressional authority through hypothetical statutes or ordinances.

Core Legal Basis and Definition

Article VI, Section 1 of the 1987 Constitution provides: "The legislative power shall be vested in the Congress of the Philippines which shall consist of a Senate and a House of Representatives, except to the extent reserved to the people by the provision on initiative and referendum."

Legislative power is the authority to enact, amend, or repeal laws. It is plenary in character, meaning Congress may legislate on any subject matter, provided it does not violate the Constitution. Limitations are classified into substantive (content of the law) and procedural (manner of enactment), plus inherent limitations arising from the nature of the power itself.

Essential Requisites and Classifications of Limitations

Substantive Limitations

These restrict what Congress can validly provide in a law:

Bill of Rights (Article III): Laws must respect due process, equal protection, non-impairment of contracts, freedom of speech/religion, etc.
Specific Prohibitions: No law establishing a state religion or prohibiting free exercise thereof (Art. III, Sec. 5); no ex post facto law or bill of attainder (Art. III, Sec. 22).
Taxation: Must be uniform and equitable (Art. VI, Sec. 28(1)); income tax law must originate exclusively in the House (Art. VI, Sec. 24).
Appropriations: Must specify the purpose and be supported by funds (Art. VI, Sec. 29).
Titles of Bills: Every bill must embrace only one subject expressed in the title (Art. VI, Sec. 26(1)).
Non-delegation: "Potestas delegata non delegari potest" — legislative power cannot be delegated, except in cases of subordinate legislation with sufficient standards.

Procedural Limitations

These govern the law-making process:

Three Readings Rule: Bills must pass three readings on separate days, with printed copies distributed three days before final passage (Art. VI, Sec. 26(2)), except when the President certifies urgency.
Origination Clause: Revenue, appropriation, and tariff bills must originate in the House of Representatives (Art. VI, Sec. 24).
Bicameral Approval and Enrollment: Passage by both houses and signing by presiding officers.

Inherent Limitations

Derived from the republican and democratic nature of the State:

Cannot pass irrepealable laws.
Cannot encroach on powers of other departments (separation of powers).
Subject to judicial review.

Landmark Supreme Court Doctrines

People v. Vera (1937): The non-delegation doctrine requires that delegation of legislative power must provide sufficient standards to guide the delegate.
Eastern Shipping Lines v. POEA (1988): Legislative discretion on what the law shall be cannot be delegated; only the power to fill in details (subordinate legislation) may be delegated if standards are clear.
Tio v. Videogram Regulatory Board (1987): The one-subject-one-title rule is liberally construed; the title need not be an index of the bill's contents.
Arroyo v. De Venecia (1997): Procedural requirements in law-making are directory, not mandatory, unless they affect substantive rights; courts generally refrain from inquiring into internal congressional procedures.
Philconsa v. Enriquez (1994): Congress cannot increase the Judiciary's appropriation recommended by the President without violating the separation of powers.

Key Exceptions, Qualifications, and Distinctions

Delegation Exceptions: Allowed to the President (emergency powers under Art. VI, Sec. 23(2)), administrative agencies (with standards), and local governments (under the Local Government Code).
Urgency Exception to Three Readings: Presidential certification dispenses with the three-day printed copy rule and allows immediate consideration.
Distinction from Executive Power: Congress cannot enact laws that effectively perform executive functions, such as implementing laws without standards (non-delegation violation).
Distinction from Initiative and Referendum: These are reserved powers of the people; Congress cannot completely withdraw them.
Common Pitfall: Confusing substantive limits with procedural ones. A bill may follow all procedures but still be void if its content violates the Bill of Rights.

Irrepealable Laws vs. Sunset Provisions: Congress cannot bind future Congresses, but laws with automatic expiration (sunset clauses) are permissible as policy choices.

How This Topic Appears in Bar Essay Questions

Typical patterns involve a hypothetical law challenged on constitutional grounds:

A bill lacking a proper title or covering multiple subjects.
An appropriation bill originating in the Senate.
A law delegating unlimited taxing power to an agency.
A statute alleged to impair obligations of contracts or violate equal protection.

Best Answer Structure:

State the general rule: Legislative power is plenary (Art. VI, Sec. 1).
Cite the specific limitation violated with codal basis.
Apply the relevant doctrine.
Conclude on validity and legal effects (e.g., void ab initio if substantive violation).

Examiners reward precise codal references and clear application over general discussion. Common mistake: Failing to distinguish between void for being unconstitutional versus void for procedural defects (latter may be cured).

Practical Application Tips

Use the mnemonic SPIN for key limitations:

Substantive (Bill of Rights, specific prohibitions)
Procedural (Three readings, origination)
Inherent (Non-delegation, separation of powers)
Non-impairment and other specific limits

Limitation Type	Example	Effect of Violation
Substantive	Ex post facto law	Void ab initio
Procedural	Failure to follow three readings	Generally directory; may be upheld unless rights prejudiced
Inherent	Irrepealable law	Invalid as to future Congresses

Key Takeaways

Legislative power is plenary but limited only by the Constitution.
Always anchor answers on specific constitutional provisions (Art. VI, Secs. 24-26; Art. III).
Master non-delegation doctrine with its exceptions — a perennial favorite.
Distinguish substantive from procedural defects carefully.
Judicial review serves as the ultimate check; courts can strike down laws exceeding these limitations.
In essays, prioritize rule-application-conclusion format with codal and doctrinal support for high scores.