Prohibition on retrospective criminal laws
Public sector guidance sheet
This material is provided to persons who have a role in Commonwealth legislation, policy and programs as general guidance only and is not to be relied upon as legal advice. Commonwealth agencies subject to the Legal Services Directions 2005 requiring legal advice in relation to matters raised in this Guidance Sheet must seek that advice in accordance with the Directions.
What is the prohibition on retrospective criminal laws?
Laws must not impose criminal liability for acts that were not criminal offences at the time they were committed. There is an exception which is discussed below in 'Can the prohibition on retrospective laws be limited?'.
Laws must not impose greater punishments than those which would have been available at the time the acts were done.
Where does the prohibition on retrospective criminal laws come from?
Australia is a party to seven core international human rights treaties. The prohibition on retrospective criminal laws is contained in article 15 of the International Covenant on Civil and Political Rights (ICCPR).
When do I need to consider the prohibition on retrospective criminal laws?
You will need to consider the prohibition on retrospective criminal laws when legislation is contemplated that:
- creates an offence for acts done before the legislation commences
- expands the range of activities that are covered by an existing criminal offence, or
- increases the maximum or mandatory punishment (term of imprisonment or monetary penalty) available for persons who have already been convicted of a criminal offence.
The prohibition may also be relevant where legislation is contemplated that:
- amends criminal law procedure that applies to trials for acts done before the legislation commences
- introduces new sentencing options that apply to acts done before the legislation commences, or
- changes parole conditions that apply to sentences of imprisonment imposed before the legislation commences.
What is the scope of the prohibition on retrospective criminal laws?
A person may not normally be prosecuted for acts that were not criminal offences at the time they were committed. Further, laws should generally not impose a greater punishment than that which would have been available at the time the acts were done. This flows from the principle that the criminal law should be sufficiently precise to enable persons to know in advance whether their conduct would be criminal.
If the punishment for an offence is reduced after an act is committed, the lesser punishment should apply to acts committed before the legislation imposing the reduction commences.
The prohibition does not extend to retrospective changes to other measures, such as procedure, provided that they do not affect the punishment to which an offender is liable. The key issue will be whether the measure that is changed is in fact a penalty. Terms of imprisonment and fines are clearly penalties, to which the prohibition potentially applies. Retrospective changes to trial practice or rules of evidence would not normally infringe the prohibition. It can be argued that changes to eligibility for parole that result in a person serving a longer sentence before being eligible for parole can be regarded as the imposition of a heavier penalty.
The prohibition only applies to laws imposing criminal liability or punishments for criminal offences. It does not apply to non-criminal sanctions, such as financial penalties imposed by a court in a civil case that does not result in a criminal conviction.
Can the prohibition on retrospective criminal laws be limited?
The prohibition on retrospective criminal laws is considered to be an absolute right. For further information see the additional information sheet on Absolute Rights.
Under article 4 of the ICCPR, countries may take measures derogating from certain of their obligations under the Covenant 'in time of public emergency which threatens the life of the nation and the existence of which is officially proclaimed'. However, the prohibition on retrospective criminal laws is specifically excluded from the obligations from which derogation is permitted.
Despite the general prohibition, in Australia, legislation creating a criminal offence may in exceptional circumstances be expressed to apply to acts committed before the legislation commences.
Under article 15(2), the prohibition does not apply if the relevant act was criminal at the time it was committed 'according to the general principles of law recognised by the community of nations'. Therefore, the retrospective criminalisation of an act that satisfied this test would not infringe the prohibition. In Polyukhovich v The Commonwealth  HCA 32 (the Polyukhovich case) (further discussed below), the High Court upheld the power of the Parliament in 1988 to legislate for the trial in Australian Courts of war crimes committed during the course of the Second World War. The limitation contained in article 15(2) will only apply in very limited circumstances. Advice should be sought in any case in which an officer believes that the limitation might apply.
Which domestic laws relate to the prohibition on retrospective criminal laws?
There is no Commonwealth legislation enshrining the prohibition on retrospective criminal laws. However, it has long been regarded as part of the common law. In the Polyukhovich case, the High Court upheld the power of the Parliament in 1988 to legislate for the trial in Australian Courts of war crimes committed during the course of the Second World War. Dawson J (in the majority of the Court) said:
the resistance of the law to retrospectivity in legislation is to be found in the rule that, save where the legislature makes its intention clear, a statute ought not be given a retrospective operation where to do so would be to attach new legal consequences to facts or events which occurred before its commencement.
Retrospective offences have been enacted in Commonwealth legislation in the following cases:
- the 'bottom of the harbour' tax evasion offences (Crimes (Taxation Offences) Act 1980)
- the war crimes offences inserted in the War Crimes Act 1945 by the War Crimes (Amendment) Act 1988
- the anti-hoax offence inserted in the Criminal Code Act 1995 by the Criminal Code Amendment (Anti-Hoax and other Measures) Act 2002.
The Government's policy on retrospective criminal offences is discussed in 'A Guide to Framing Commonwealth Offences, Civil Penalties and Enforcement Powers', released in December 2007. A link to this document is contained in the 'Where can I read more about the prohibition on retrospective criminal laws' section below.
What other rights and freedoms relate to the prohibition on retrospective criminal laws?
The prohibition on retrospective criminal laws may be relevant to the right to a fair trial.
Articles from relevant Conventions
International Covenant on Civil and Political Rights
- No one shall be held guilty of any criminal offence on account of any act or omission which did not constitute a criminal offence, under national or international law, at the time when it was committed. Nor shall a heavier penalty be imposed than the one that was applicable at the time when the criminal offence was committed. If, subsequent to the commission of the offence, provision is made by law for the imposition of the lighter penalty, the offender shall benefit thereby.
- Nothing in this article shall prejudice the trial and punishment of any person for any act or omission which, at the time when it was committed, was criminal according to the general principles of law recognized by the community of nations.
Where can I read more about the prohibition on retrospective criminal laws?
- Australian Government: 'A Guide to Framing Commonwealth Offences, Civil Penalties and Enforcement Powers', December 2007