This is a single section from Chapter 11. Read the full chapter here.

Does the legislation have direct retrospective effect?

Legislation should not have retrospective effect.


The starting point is that legislation should not have retrospective effect. It should not interfere with accrued rights and duties.

Legislation might have a direct legislative effect when it:


  • applies to events or actions that have already taken place;
  •  prevents a person from relying on a right or defence that existed at the time they undertook the conduct that those rights or defences related to;
  •  punishes a person or imposes a burden or obligation in respect of past conduct.


The presumption against retrospective legislation is strongest in respect of criminal offences. People should not be made criminally liable for past actions that were not prohibited at the time of commission. Where the penalty that attaches to an offence is increased between commission and conviction, the lesser penalty should also apply.

Retrospective legislation might however be appropriate where it is intended to:


  • be entirely to the benefit of those affected;
  • validate matters that were generally understood and intended to be lawful, but were in fact unlawful as a result of a technical error;
  • decriminalise conduct (for example, s 7 of the Homosexual Law Reform Act 1986);
  • address a matter that is essential to public safety;
  • provide certainty as a result of litigation (discussed in more detail in 11.4 below);
  • (in limited circumstances) make changes to tax law or other budgetary legislation.


Where direct retrospective effect is intended, this must be clearly stated in the legislation and must be capable of justification. If it is not expressly stated, there is the risk that the courts will apply the presumption that legislation does not have retrospective effect.

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