I. Why the Topic Matters

Penal statutes in the Philippines change for many reasons: policy shifts, recalibration of penalties, decriminalization of conduct, modernization of definitions, or alignment with constitutional and human-rights standards. When Congress repeals or amends a penal law, the immediate practical questions are predictable and high-stakes:

Can a person still be prosecuted for an act committed before the new law took effect?
If already convicted, can the penalty be reduced—or the person released?
If the amendment is harsher, can it apply to earlier conduct?
What happens to cases currently under investigation, on trial, or on appeal?

Philippine criminal law answers these through a mix of constitutional commands (especially the ban on ex post facto laws), the Revised Penal Code (RPC) (notably Articles 21, 22, and 366), general principles of statutory construction, and the criminal procedure framework.

II. Constitutional and Statutory Foundations

A. The legality principle and prospectivity (no punishment without a prior law)

Two bedrock norms control timing questions:

Nullum crimen, nulla poena sine lege (no crime, no punishment without law).
Prospectivity of penal laws: as a rule, penal laws apply only to acts committed after their effectivity.

In Philippine terms, this appears most clearly in Article 21, RPC: no felony shall be punished by any penalty not prescribed by law prior to its commission. This reflects due process and the constitutional architecture protecting liberty.

B. The ex post facto prohibition

The Constitution prohibits ex post facto laws. In effect, the State may not retroactively:

make innocent conduct criminal,
aggravate a crime or make it greater than it was when committed,
increase the punishment,
change rules of evidence to make conviction easier, or
alter legal rules in a way that substantially disadvantages the accused for past acts.

This constitutional barrier is often the decisive reason harsher penal amendments cannot be applied to prior conduct.

C. Retroactivity of penal laws favorable to the accused (lex mitior)

Philippine law recognizes the principle of lex mitior: a penal law favorable to the accused is given retroactive effect. This is codified in Article 22, RPC, with a crucial limitation: it does not retroact in favor of a person who is a habitual delinquent (as defined in Article 62 of the RPC).

D. Repeal-specific rule in the RPC

Article 366, RPC addresses repeal: as a baseline, acts committed before repeal remain governed by the law at the time of commission, but subject to Article 22—meaning if the new legal regime is more favorable, the accused benefits.

III. Core Concepts: Repeal vs. Amendment (and related distinctions)

A. Repeal

A repeal is the abrogation of a penal statute (or a penal provision). It may be:

Express repeal: the new law explicitly states the old law or provision is repealed.
Implied repeal: the new law is so inconsistent with the old, or so comprehensive, that both cannot stand together.

Implied repeal is disfavored; courts try to reconcile statutes if possible.

B. Amendment

An amendment modifies an existing law without necessarily abolishing it. Amendments may:

alter the definition/elements of the offense,
adjust penalties (raise, lower, reclassify),
add or remove qualifying/aggravating/mitigating circumstances,
change defenses or exclusions,
revise thresholds (e.g., monetary values, quantities).

C. Repeal with reenactment vs. repeal with decriminalization

A crucial statutory-construction distinction:

Repeal with reenactment/substitution: the legislature repeals an old penal rule while substantially reenacting it in a new form (often reorganized or updated). Liability frequently continues, but the applicable rule depends on timing and whether the new scheme is more or less favorable.
Repeal that decriminalizes: the legislature removes criminality—either explicitly or by deleting the penal sanction. This is typically most favorable and triggers retroactive benefit under Article 22 (subject to habitual delinquency limits), unless Congress clearly provides a different transitional rule consistent with constitutional limits.

D. “Saving clauses”

Repealing or amendatory laws often include saving clauses (transitory provisions), e.g., language that pending cases “shall continue” under the old law, or that liabilities incurred “shall not be affected.” In the Philippines, saving clauses matter most for:

special penal laws, and
situations where the legislature’s transitional intent needs to be enforced.

For offenses within the RPC, Article 366 functions as a built-in reference point, but legislative saving clauses can still be relevant to clarify application and procedure.

IV. General Rules on Temporal Application (Philippine setting)

Rule 1: A penal law that is harsher applies prospectively only

If the new law:

increases the penalty,
broadens the definition of the offense,
reduces defenses,
adds qualifying circumstances increasing the punishment, it generally cannot apply to acts committed before effectivity because of the ex post facto prohibition and Article 21’s legality principle.

Rule 2: A penal law that is more lenient applies retroactively

If the new law:

lowers the penalty,
narrows the definition (making conviction harder),
removes qualifying circumstances,
creates additional defenses/exemptions, it generally benefits persons whose acts occurred before effectivity—including those with pending cases, cases on appeal, and even those already serving sentence—by virtue of Article 22 (with the habitual delinquent exception).

Rule 3: Determine favorability by comparing the entire legal consequence, not just one line of the statute

“Favorable” is not always obvious. A law may lower the maximum imprisonment but raise fines, remove eligibility for certain relief, or alter accessory penalties. A proper comparison considers:

principal penalty range,
accessory penalties,
civil/confiscation consequences tied directly to conviction,
disqualifications linked to the penalty classification (e.g., effects on subsidiary imprisonment, accessory penalties, and sometimes eligibility thresholds in related laws).

Rule 4: If the act is no longer a crime under the new regime, prosecution generally cannot continue

If the repeal or amendment removes an essential element or the penal sanction such that the conduct is no longer criminal, continuing prosecution typically fails because:

there is no longer a punishable offense under the new, controlling regime, and
Article 22’s logic favors extinguishing criminal liability for covered acts (again, subject to the habitual delinquent limitation in the statutory text, and to the specifics of the new law’s transitional provisions).

V. Effects at Different Case Stages

A. Before a case is filed (investigation stage)

If a repeal/amendment takes effect before filing and is favorable:

prosecutors should evaluate whether probable cause still exists under the new legal landscape;
if the conduct has been decriminalized or the elements changed so the act no longer fits, filing should not proceed.

If the new law is harsher, it generally cannot be used to prosecute older conduct; charging should be based on the law in force at the time of commission.

B. After filing but before judgment (trial stage)

If a favorable amendment/repeal occurs during trial:

the accused may invoke Article 22;
courts may dismiss if the act is decriminalized, or
proceed but impose the more lenient penalty if conviction remains possible.

If the amendment is harsher:

the court cannot apply the harsher rule to the prior act without violating ex post facto constraints.

C. During appeal

A favorable penal law that takes effect while the case is on appeal should be applied by the appellate court, including:

reduction of penalty,
reclassification of the offense to a lesser one (if the new definition is narrower and fits only a lesser offense),
dismissal if decriminalized.

Philippine appellate practice in criminal cases is strongly protective: courts may correct penalties in favor of the accused even when not specifically assigned as error, because liberty is at stake and penalties must conform to law.

D. After final judgment (execution stage)

Even after finality, favorable penal laws may still benefit a convict:

sentence modification to the lower range,
recomputation of penalty,
possible release if the lawful maximum under the new favorable regime has already been served,
correction of accessory penalties where the principal penalty changes classification.

Procedurally, relief may be sought through motions in the trial court (for correction/recomputation), petitions affecting detention legality, or other appropriate remedies depending on the posture (the key point is that a person should not remain imprisoned under a penalty no longer authorized by the controlling favorable law).

VI. Effects of Repeal (Focused Discussion)

A. Repeal that keeps criminality (repeal with reenactment/substitution)

When the old law is repealed but the conduct remains criminal under a new statute:

acts committed before effectivity are usually judged under the old definition and penalty, unless the new statute is more favorable and can be applied retroactively (Article 22).
if the new statute is harsher, it governs only future acts.

Key practical issue: elements may change. If the new law modifies elements (e.g., adds a requirement), then:

a person cannot be convicted under the new definition for a past act if that new definition is stricter (ex post facto concerns),
but the person may benefit if the new definition is narrower and thus excludes the conduct (favorable).

B. Repeal that removes criminality (decriminalization)

If repeal results in the conduct no longer being criminal:

pending prosecutions typically cannot proceed (no punishable offense),
convictions tied solely to that crime should not continue to justify imprisonment under the favorable change,
the State may still pursue non-criminal regulatory, administrative, or civil consequences if a separate legal basis exists.

C. Repeal with a saving clause

If the repealing law includes a saving clause preserving pending cases or prior liabilities:

prosecutions for past acts can continue under the transitional rule so long as constitutional limitations are respected (chiefly, no retroactive harsher effect beyond what existed at the time of the act).
saving clauses are especially important in special penal laws, where there is no internal RPC equivalent of Article 366 automatically embedded in the text of every special statute.

VII. Effects of Amendment (Focused Discussion)

A. Amendment changing the penalty only

This is the most common scenario.

Penalty decreased (mitigatory amendment)
- Retroactive in favor of accused (Article 22), except habitual delinquent limitation.
- Courts should impose the lighter penalty even for older acts.
- Those already serving sentence may seek recomputation.
Penalty increased (aggravatory amendment)
- Prospective only; cannot apply to older acts.
Penalty reclassified (e.g., changes in ranges or nomenclature)
- Impacts:
  - accessory penalties that attach by law to certain principal penalties,
  - eligibility thresholds tied to penalty length or classification (in related statutes),
  - jurisdictional thresholds in some contexts (although jurisdiction typically attaches upon filing and is not easily divested midstream without express legislative direction).

B. Amendment changing the elements of the offense

An amendatory law may:

broaden the offense (more conduct criminalized): prospective only as to the broadened coverage.
narrow the offense (less conduct criminalized): retroactive benefit—older conduct outside the narrowed definition should not be punished.

Elements changes create pleading and proof implications:

An information must allege all elements of the offense under the applicable law.
If the applicable law changes and the prosecution insists on proceeding under a different framework, the information may require amendment—subject to rules on substantial amendments and the accused’s rights.

C. Amendment adding/removing qualifying circumstances

Qualifying circumstances change the nature of the offense and usually increase penalty exposure. If added later:

it cannot be used to qualify prior conduct (ex post facto problem). If removed or limited:
it may benefit the accused retroactively.

D. Amendment affecting defenses, exemptions, or exclusions

If a new law expands defenses or exemptions (e.g., raises the age-related exclusion or creates new justifications):

it is typically favorable and retroactive under Article 22 principles.

VIII. How to Decide Whether the New Law Is “Favorable” (Practical Method)

A disciplined comparison usually follows this order:

Identify the law in force at the time of commission (old regime).
Identify the law in force now (new regime).
Compare:
- Definition: Is the act still covered?
- Penalty range: minimum/maximum, and classification of penalties.
- Accessory penalties: disqualification, interdiction, suspension, etc., if tied to classification.
- Direct statutory consequences tied to conviction under that provision (e.g., mandatory forfeiture provisions specific to the offense).
Choose the regime that is overall more beneficial to the accused, applying Article 22 (subject to habitual delinquent exception).

A common pitfall is comparing only maximum imprisonment while ignoring:

accessory penalties,
minimum terms affecting confinement reality,
mandatory fine/forfeiture components.

IX. Special Topics That Commonly Complicate Application

A. Continuing crimes and “straddling” effectivity dates

Some offenses are continuing by nature (the wrongful condition persists over time). When conduct begins before effectivity but continues after:

the post-effectivity portion can bring the case within the new law’s operation without violating ex post facto principles, because part of the punishable conduct occurs after effectivity.
however, careful legal characterization matters; not every repeated or extended harm is legally a continuing offense.

B. Changes that look “procedural” but affect substantial rights

Generally, procedural changes apply to pending actions, while substantive penal changes follow Articles 21/22 and ex post facto limits. But the line is not always clean. For instance:

a rule change that substantially lowers the evidentiary burden or removes a protection may be treated as ex post facto in effect if applied retroactively;
extensions of prescriptive periods raise sensitive retroactivity questions, especially if they revive liability that would otherwise have already been extinguished.

C. Jurisdictional effects when penalties change

Courts often hold that jurisdiction attaches upon filing under the law and facts then controlling, and is not defeated by later statutory changes—unless the new law clearly mandates transfer or reallocation. Even if jurisdiction stays, the penalty to be imposed may still need adjustment under the favorable-law principle.

D. Special penal laws and the RPC’s supplementary role

The RPC is generally suppletory to special penal laws (Article 10, RPC), and the Constitution’s ex post facto ban applies across the board. Favorable retroactivity (lex mitior) is a widely applied principle in penal interpretation even when the offense is statutory (special law), though application details may depend on the structure and transitional provisions of the special statute.

X. Civil Liability and Other Consequences After Repeal/Amendment

A. Civil liability “ex delicto” vs. civil liability from other sources

Criminal cases often carry a civil dimension. When criminality is removed or prosecution is barred:

Civil liability ex delicto depends on the existence of a crime. If the act is no longer criminal under the controlling regime, the “crime-based” civil source may disappear.
But the same facts may still create civil liability under other sources (e.g., quasi-delict, contract, unjust enrichment), which can be pursued through the appropriate civil action.

B. Restitution, forfeiture, and confiscation

If confiscation/forfeiture is a mandatory statutory consequence of conviction under a penal provision, repeal/amendment can affect its basis, depending on:

whether the conviction remains legally supportable under the favorable regime,
whether forfeiture is independent (regulatory) rather than purely penal.

C. Accessory penalties and collateral legal disabilities

Penalty reductions can change:

the presence or duration of accessory penalties (when accessory penalties are tied to the principal penalty by the RPC),
the classification of the offense for some collateral consequences embedded in law.

XI. Practitioner’s Checklist (Philippine Practice Orientation)

Pin down dates: commission of the act; effectivity date of the new law; procedural milestones (filing, arraignment, judgment, appeal).
Classify the change: repeal vs amendment; decriminalization vs reenactment; penalty-only vs elements changed.
Apply the constitutional filter: if harsher and retroactive → barred.
Apply Article 22: if favorable → retroactive, except habitual delinquent limitation.
Apply Article 366 when dealing with repeal (within RPC logic), and read transitional provisions/saving clauses carefully (especially for special laws).
Compute practical consequences: revised penalty, accessory penalties, and whether time served exceeds the lawful maximum under the favorable regime.
Choose the proper remedy based on posture: dismissal/motion, penalty recomputation, modification on appeal, or post-judgment relief consistent with the person’s detention status.

XII. Synthesis

In Philippine criminal law, repeal or amendment of penal statutes operates under a stable hierarchy of principles:

No retroactive harsher penal law (Constitution; Article 21, RPC).
Retroactive application of favorable penal law (Article 22, RPC), subject to the habitual delinquent limitation.
Repeal is handled with explicit attention to timing and favorability (Article 366, RPC), and in special laws, by reading the legislature’s transitional intent (saving clauses) alongside constitutional constraints.

The practical legal effect is that legislative change can (1) extinguish criminal liability, (2) reduce penalties and shorten confinement, (3) prevent use of new harsher rules against past conduct, or (4) preserve prosecution under transitional design—while courts remain constitutionally bound to ensure that no person is punished under a rule that did not exist (or is not legally applicable) at the time of the act, and that favorable penal changes reach those the law intends to benefit.