Retroactive Legislation

An ''ex post facto'' law (from ) is a law that retroactively changes the legal consequences (or status) of actions that were committed, or relationships that existed, before the enactment of the law. In criminal law, it may criminalize actions that were legal when committed; it may aggravate a crime by bringing it into a more severe category than it was in when it was committed; it may change the punishment prescribed for a crime, as by adding new penalties or extending sentences; or it may alter the rules of evidence in order to make conviction for a crime likelier than it would have been when the deed was committed.

Conversely, a form of ''ex post facto'' law commonly called an amnesty law may decriminalize certain acts. (Alternatively, rather than redefining the relevant acts as non-criminal, it may simply prohibit prosecution; or it may enact that there is to be no punishment, but leave the underlying conviction technically unaltered.) A pardon has a similar effect, in a specific case instead of a class of cases (though a pardon more often leaves the conviction itself – the finding of guilt – unaltered, and occasionally pardons are refused for this reason). Other legal changes may alleviate possible punishments (for example by replacing the death sentence with lifelong imprisonment) retroactively. Such legal changes are also known by the Latin term ''in mitius''.

Some common-law jurisdictions do not permit retroactive criminal legislation, though new precedent generally applies to events that occurred before the judicial decision. ''Ex post facto'' laws are expressly forbidden by the United States Constitution in Article 1, Section 9, Clause 3 (with respect to federal laws) and Article 1, Section 10 (with respect to state laws). In some nations that follow the Westminster system of government, such as the United Kingdom, ''ex post facto'' laws are possible, because the doctrine of parliamentary supremacy allows Parliament to pass any law it wishes. In a nation with an entrenched bill of rights or a written constitution, ''ex post facto'' legislation may be prohibited or allowed, and this provision may be general or specific. For example, Article 29 of the Constitution of Albania explicitly allows retroactive effect for laws that alleviate possible punishments.

''Ex post facto'' criminalization is also prohibited by Article 7 of the European Convention on Human Rights, Article 15(1) of the International Covenant on Civil and Political Rights, and Article 9 of the American Convention on Human Rights. While American jurisdictions generally prohibit ''ex post facto'' laws, European countries apply the principle of ''lex mitior'' ("the milder law"). It provides that, if the law has changed after an offense was committed, the version of the law that applies is the one that is more advantageous for the accused. This means that ''ex post facto'' laws apply in European jurisdictions to the extent that they are the milder law.

''Ex post facto'' laws by country

Australia

Australia has no strong constitutional prohibition on ''ex post facto'' laws, although narrowly retrospective laws might violate the constitutional separation of powers principle. Australian courts normally interpret statutes with a strong presumption that they do not apply retrospectively.

Retrospective laws designed to prosecute what was perceived to have been a blatantly unethical means of tax avoidance were passed in the early 1980s by the Fraser government (see Bottom of the harbour tax avoidance). Similarly, legislation criminalising certain war crimes retrospectively has been held to be constitutional (see ''Polyukhovich v Commonwealth'').

The government will sometimes make a press release that it intends to change the tax law with effect from the date and time of the press release, before legislation is introduced into parliament.

Australia participated in drafting the Universal Declaration of Human Rights and was an original signatory in 1948. The Declaration includes a prohibition on retrospectively holding anyone guilty of a penal offence that was not an offence at the time it was committed. The Australian Human Rights Commission states the Declaration is an "expression of the fundamental values which are shared by all members of the international community" but "does not directly create legal obligations for countries."

Australia is a party to the International Covenant on Civil and Political Rights. The implementation of retrospective criminal laws is expressly prohibited by the Covenant. Australia is also a party to the Optional Protocol to the International Covenant on Civil and Political Rights. The Protocol enables individuals subject to the jurisdiction of a state party to file complaints with the United Nations Human Rights Committee for that state party's non-compliance with the International Covenant on Civil and Political Rights.

Brazil

According to the 5th Article, section XXXVIide Emenda Constitucional nº 107, de 2020
Casa Civil (in Portuguese) of the Brazilian Constitution, laws cannot have ''ex post facto'' effects that affect acquired rights, accomplished juridical acts and ''res judicata''.

The same article in section XL prohibits ''ex post facto'' criminal laws. Like France, there is an exception when retroactive criminal laws benefit the accused person.

Canada

In Canada, ''ex post facto'' criminal laws are constitutionally prohibited by paragraph 11(g) of the Charter of Rights and Freedoms. Also, under paragraph 11(i) of the Charter, if the punishment for a crime has varied between the time the crime was committed and the time of sentencing following a conviction, the convicted person is entitled to the lesser punishment. Due to section 1 and section 33 of the Charter of Rights and Freedoms these rights are not absolute, and may be overridden.

The Canada sex offender registry, which went into effect on December 15, 2004, is somewhat retroactive. When the registry was created, all offenders who were on the Ontario sex offender registry, which was created in 2001, were required to register on the national registry. In addition, sex offenders in all provinces who were serving a sentence (whether imprisoned or on probation or parole) on December 15, 2004, were required to register, regardless of when their offense and conviction occurred. However, the registry was not retroactive to anybody who had completed their sentence by late 2004 and was not on the Ontario registry. Canadian courts have never ruled on the somewhat retroactive nature of the sex offender registry, since this seems to have never been challenged.

Sex offender registration was not mandatory for sex offenders until 2011, and had to be ordered by a judge. Sex offender registration was seemingly mandatory for people convicted before December 15, 2004, who were serving a sentence on that date, but was only optional for sex offenders convicted between December 15, 2004, and January 1, 2011.

Because section 11 of the Charter is among the sections that can be overridden under section 33 (the notwithstanding clause), Parliament could in theory enact ''ex post facto'' laws by invoking section 33. However, the federal Parliament, which has exclusive jurisdiction over criminal law, has never attempted to enact an ''ex post facto'' law (or any other law) using section 33.

The Charter prohibition applies only to criminal law. Changes to civil law in Canada can be, and occasionally are, enacted ''ex post facto''. In one example, convicted murderer Colin Thatcher was ordered to forfeit proceeds from a book he had published (after being paroled from prison) under a Saskatchewan law. Although the law was passed long after Thatcher's murder conviction, the courts have ruled that such laws prescribe only civil penalties (as opposed to additional criminal penalties) and are thus not subject to Charter restrictions.

Croatia

Article 90 of the Constitution of Croatia states that "only individual provisions of a law may have a retroactive effect for exceptionally justified reasons". According to Croatian legal scholar , this means that "a law cannot be applied retroactively as a whole, and regulations enacted pursuant to statutory authority can never be applied retroactively".

Denmark

Following the liberation of Denmark from Nazi occupation in 1945, the Folketing, heavily influenced by the Frihedsråd, passed a special law (Lov Nr. 259 af 1. Juni 1945 om Tillæg til Borgerlig Straffelov angaaende Forræderi og anden landsskadelig Virksomhed, colloquially ''landsforræderloven'' (the traitor law) or ''strafferetstillægget'' (the penal code addendum)), temporarily reintroducing the death penalty (previously abolished in 1930) for acts of treason committed during German occupation. Passed on 1 June 1945, the law applied to actions performed subsequent to 9 April 1940, unless those actions were done under orders from the government prior to 29 August 1943. With this authorization, 103 death sentences were issued, of which 46 were carried out.

Finland

Generally, the Finnish legal system does not permit ''ex post facto'' laws, especially those that would expand criminal responsibility. They are not expressly forbidden; instead, the ban is derived from more general legal principles and basic rights. In civil matters, such as taxation, ''ex post facto'' laws may be made in some circumstances.

Former Minister of the Interior Päivi Räsänen became subject of a criminal investigation about suspected agitation against an ethnic group in late 2019 over her text concerning homosexuality, which was published online in 2004. The statute of limitations for said charge is five years, which has led the case to be interpreted as ''ex post facto''. However, agitation against an ethnic group is a ''perpetuating crime'', and the statute of limitations only begins once the offending material has been removed from public viewing. The investigation has still been characterized as strange, as Räsänen's text is hardly the only material online or otherwise that could be viewed as agitation against an ethnic group, and the demarcation between who should and who should not be prosecuted for publishing and/or making such material available is unclear.

Historically there have been three exceptional instances when ''ex post facto'' criminal laws have been used in Finland.

# Following the Finnish Civil War of 1918, the Parliament of Finland passed a law setting up tribunals to try suspected rebels. These tribunals issued death sentences in many cases, although very few of those accused could have committed a crime that carried the death penalty under Finnish law in force during the war. Several hundred people were executed under what was arguably an ''ex post facto'' legal arrangement. During the war, and before the tribunals were set up, thousands of people had been executed without trial by both sides. However, once this phase of the civil war ended, amnesty laws were passed. Thus, the legality of the actions of the government or the participants of either side of the war cannot be legally contested anymore.
# After World War II, Finland was under pressure to convict political leaders whom the Allied powers considered responsible for Finnish involvement in the war. An ''ex post facto'' law was passed in the autumn of 1945 to permit prosecution for war responsibility, and eventually eight politicians were convicted. In another post-war case, the weapons cache case, an ''ex post facto'' law was passed in 1947 so that military personnel could be prosecuted for unofficially preparing for guerrilla resistance in case of Soviet occupation.
# During World War II, desertion, draft dodging and conscientious objection were punishable by death or jail. Amnesty laws were passed after World War II to free deserters and draft dodgers from imprisonment and further prosecution and allow them to return home without further legal consequences.

France

In France, so-called "''lois rétroactives''" (retroactive laws) are technically prohibited by Article 2 of the Code Civil, which states that: "Legislation provides only for the future; it has no retrospective operation". In practice, however, since the Code Civil does not have the status of constitutional legislation and can therefore be overruled by subsequent laws, the Conseil Constitutionnel has determined that retroactive laws can be passed within certain limits – such as in the case of financial or tax legislation –, particularly where it is considered to be in the "general interest"; this has been demonstrated by a series of decisions handed down by the Conseil Constitutionnel concerning retroactive tax laws.

However, in criminal law, ''ex post facto'' sanctions are effectively forbidden as per Article 112-1 of the French Penal Code, except in cases wherein the retroactive application benefits the accused person (called retroactivity ''in mitius''). They are also considered unconstitutional, since the principle of non-retroactivity is laid down in Article 8 of the Declaration of the Rights of Man and of the Citizen, which has constitutional status under French law. The ''épuration légale'' trials held after the 1944 liberation of France introduced the status of ''indignité nationale'' for Nazi collaborators as a way to avoid ''ex post facto'' law.

Germany

Article 103 of the German basic law requires that an act may be punished only if it has already been punishable by law at the time it was committed (specifically: by ''written'' law, Germany following civil law).

Robert A. Taft, at the time a U.S. Senator from Ohio, asserted that the Nuremberg Trials following World War II were based on ''ex post facto'' law because the Allies did not negotiate the London Charter, which defined crimes against humanity and created the International Military Tribunal, until well after the acts charged. Others, including the International Military Tribunal, argued that the London Charter merely restated and provided jurisdiction to prosecute offenses that were already made unlawful by the Kellogg-Briand Pact, the Covenant of the League of Nations, and the various Hague Conventions.

William O. Douglas complained that the Allies were guilty of "substituting power for principle" at Nuremberg Trials because the actions of the defendants were lawful in the 1930s Germany. He contended that the Nuremberg Trials were implementing laws after the fact (that is, ex post facto) "to suit the clamor of the time." American Chief Justice Harlan Stone, likewise, called the Nuremberg Trials a "fraud" because of the ex post facto laws.

The problem of ''ex post facto'' law was also relevant in the 1990s after German reunification as there was a discussion about the trials against East German border troops who killed fugitives on the Inner-German border ( ''Mauerschützen-Prozesse'' - ''Wall-shooters'/ -guards' trials''). German courts in these cases recurred to the Radbruch formula.

Hungary

In 2010, the Hungarian National Assembly established a 98% punitive tax on any income over two million forints received either as a retirement package or as severance pay in the previous five years in the government sector.

India

In India, without using the expression "''ex post facto law''", the underlying principle has been adopted in the article 20(1) of the Indian Constitution in the following words:

Further, what article 20(1) prohibits is conviction and sentence under an ''ex post facto'' law for acts done prior thereto, but not the enactment or validity of such a law. There is, thus, a difference between the Indian and the American positions on this point; whereas in the United States, an ''ex post facto'' law is in itself invalid, it is not so in India. The courts may also interpret a law in such a manner that any objection against it of retrospective operation may be removed.

An example for retrospective law in India is the Karnataka Schedule Caste and Scheduled Tribes (Prohibition of Transfer of Certain Lands) Act, 1978 in the state of Karnataka.

Indonesia

The Indonesian Constitution prohibits trying citizens under retroactive laws in any circumstance. This was tested in 2004 when the conviction of Masykur Abdul Kadir, one of the Bali bombers, under retroactive anti-terrorist legislation was quashed.

Iran

''Ex post facto'' laws, in all contexts, are prohibited by Article 169 (Chapter 11) of the Iranian Constitution.

Ireland

The imposition of retroactive criminal sanctions is prohibited by Article 15.5.1° of the Irish Constitution. Retroactive changes of the civil law have also been found to violate the constitution when they would have resulted in the loss in a right to damages before the courts, the Irish Supreme Court having found that such a right is a constitutionally protected property right.

Israel

Israel enacted the 1950 Nazis and Nazi Collaborators (Punishment) Law for the purpose of punishing acts that occurred during the Second World War and the Holocaust, when Israel did not exist as a state. The law was used to punish Adolf Eichmann