Ex Post Facto Laws: An Overview


Ordinarily, a person is governed by the law existing at that particular period. However, the legislative authorities are vested with the power to bring the law in existence with retrospective effects. Here, retrospective effects mean applicability of law from the back-date, i.e. before the date of enactment. Thus, ex post facto law is a law which imposes penalties retrospectively, that is upon the acts already done, or which increases the penalty for the past acts. It is also known as “Doctrine of Retrospective”. Article 20(1) of the Constitution gives protection against the execution of ex post facto laws in criminal matters. However, in other issues, such as tax, retrospective laws can be enforced to make existing law fair and reasonable. Besides India, there is a strict prohibition of ex post facto laws in many countries such as the U.S.A., South Africa, Canada. The necessity of giving protection against these laws are very well addressed in criminal matters where the range of penalty and offence are of aggressive.

Provisions in other Constitution

The South Africa Constitution

Sec 35(3)(l) of the South African Bill of Rights prohibits ex post facto laws. It states that no individual would be convicted for an act or omission that was not an offence under either national or international law at the time it was committed or omitted.

Human Rights Act, 2004 of Australia

Sec 25 of the Human Rights Act,2004 of Australian Capital Territory Legislative Assembly that recognizes the fundamental Human Rights of an Individual state that “no person should be held guilty for a criminal offence when such offence was not the criminal offence when such action was taken or Person is not liable for a higher rate pf penalty for the offence which was done before the levy of such penalty”.

European Convention of Human Rights

Article 7 of the European Convention of Human Rights states that no individual shall be held guilty of any criminal offence on account of any act or omission which did not constitute a criminal offence under national and international laws at the time when it was committed nor shall a heavier penalty be imposed than the one was applicable at the time criminal offence was committed.

The U.S. Constitution

The U.S. Constitution expressly prohibits ex post facto law under clause 3 of Article-1 Section 9 concerning the federal laws and Article 1, Section 10 concerning state laws.

The Canada Constitution

Section 11(g) of the Charter of Rights and Freedom states that any person charged with an offence has the right not to be found guilty on account of an act or omission unless, at the time of such Act or omission, it constituted an offence under the Canadian or International law or was criminal according to the general principle of law recognized by the community of the nation. Further, Section 11(i) states that if the punishment for the offence has been varied between the time of offence and time of imprisonment, then the benefit of lesser punishment is available.

The Japan Constitution

Article 39 of the constitution of Japan prohibits the retroactive application of laws. It states that no person shall be liable for an act which was lawful at the time it was committed.

Scope of Article 20(1)

Article 20(1) is divided into two parts –

  • No person is to be convicted of an offence except for violating the law in force prevailing at the time of the commission of an act charged as an offence.                 

Illustration – Section 304B I.P.C., was enacted on 19-11-1986 making a dowry death punishable as an offence under the Indian Penal Code. It means Section 304B cannot be applied to a dowry death which took place in 1984, i.e. before its enactment.

  • It prevents the imposition of a higher penalty on the person, which is greater than what he might have incurred at the time he committed the offence.

Illustration- X committed an offence in 1947 under the Prevention of Corruption Act which then prescribed the punishment of imprisonment or fine or both. In the year 1949, by an amendment, such punishment is increased. It means that “X” cannot be made liable for the severer punishment.

Constitutional validity

Calder v Bull[1]

The Court held that if the following laid down test is met then only protection against ex post facto laws would be given in the matter of crime. They are –

  1. Made an innocent action done before the passing of law as criminal.
  2. Aggravated a crime or made it more significant than it was when committed.
  3. Imposed a greater punishment than the law annexed to the crime when committed.
  4. Altered the legal rules of evidence

Pralhad Krishna Kurane v The State of Bombay[2]

An application made under Article 226 of the Constitution of India by a person who was originally detained under an order dated 1/4/1948 under the Bombay Public Security Measures Act. On 26/2/1950 the Preventive Detention Act,1950 came into force followed by the introduction of The Preventive Detention (Amendment) Act in 22/2/1951. The applicant contended that the order of detention which was in effect at the time of commencement of the Amending Act was not valid.

The Court held that immunity against the ex post facto law is extended only against punishment by courts for a criminal offence. It thus can -not be claimed against preventive detention.

K.Satwant Singh v State of Punjab[3]

The petitioner committed an offence punishable under Section 420 of I.P.C. Under the said provision, there is no minimum sentence or fine has been defined. Later, in 1943, an ordinance laid down the minimum penalty which a court must compulsorily inflict on a person convicted under Section 420 of I.P.C.

The Supreme Court held that Article 20(1) was not infringed by the trial of the petitioner under the ordinance because the minimum penalty prescribed by it could not be said to be greater than what could be inflicted on petitioner under the law in force at the time offence was committed by him.

Rattan Lal v State of Punjab[4]

The appellant committed house trespass and tried to outrage the modesty of a girl aged 7 years. He was sent up for trial before the magistrate and who in turn convicted him under Section 451 and 354 of the Indian Penal Code and sentenced him to 6 months rigorous imprisonment.

This appeal by special leave raises the question of jurisdiction of an appellant court to exercise its power under Section 6 of the Probation of Offenders Act,1958 in respect of an accused who was convicted by the trial court before the Act.

The Court held that Ex post facto law which only mollifies the rigour of criminal law does not fall within the prohibition. This is not a case where the Act which was not offence before the Act, is made offence or increased the penalty. This is an instance where neither the ingredients of the offence nor the limits of a sentence are disturbed, but a provision is made to help the reformation of an accused through the agency of the Court. Thus, it is an ex post facto law which has a retrospective operation.

The State of West Bengal v S.K.Ghosh[5]

In this case, a government servant embezzled government money before August 1944, when he was suspended. An ordinance, dated August 23, 1944, provided that from the property of a person convicted for embezzlement, the amount embezzled by him was to be forfeited.

The ordinance was held valid as it did not impose a penalty within Article 20(1), but merely laid down a method of recovering the amount belonging to the government which had been embezzled.

Mohan lal v State of Rajasthan[6]

In this case, the appellant had admitted the theft of contraband substance before the enforcement of the Narcotics Drugs Psychotropic Substances Act,1985( NDPS Act). The appellant raised an issue that the offence committed by him should be covered under the Opium Act as that was the law at the time of the commission of an offence. If he is convicted under section 18 of the NDPS Act, it will amount to retrospective operation of the law imposing a penalty, which is prohibited under Article 20(1).

The Court held that what is prohibited under Article 20(1) is only a conviction or sentence under the ex post facto law and not trial thereof. Such trial under a procedure different from what obtained at the time of the commission of the offence or by a court different from that which had the competence at the time cannot “ipso facto” be held as unconstitutional.


Protection against the ex post facto law in criminal cases is adequately addressed by Article 20(1) of the Constitution. The objective of criminal law is to prevent the occurrence of crime,

to maintain law and order, to deter the offender from committing the criminal Act in future and not to punish the offender to an extreme and harsh condition. It is the fundamental right of a human being that is to be treated fairly by the law, and thus such protections act as an aid to the offender from levy of harsh punishments which came into force after the commission of an act.

Making a retrospective effect is constitutional in case of civil matters as there are many circumstances where laws need to be revised to remove certain anomalies in the law. The sole purpose is to bring change in the existing law for the betterment, keeping in mind the legal intention. Therefore, it is right to conclude that protection existing against the implication of ex post facto laws is within the power of the constitution.









Frequently Asked Questions

  1. Define ex post facto laws?
  2. What are the provisions in various legislations?
  3. Explain Article 20(1) of the Indian Constitution?
  4. What are the important judicial pronouncements?

[1] Calder v. Bull, 3 U.S. 3 Dall. 386 386 (1798)

[2] AIR 1952 Bom 1, (1951) 53 BOMLR 717, ILR 1952 Bom 134

[3] 1960 AIR 266, 1960 SCR (2) 89

[4] 1965 AIR 444, 1964 SCR (7) 676

[5]  1963 AIR 255, 1963 SCR (2) 111

[6] AIR 2015 SC 2098)

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