The time of operation and default assumptions of drafting determine how statutes apply to past events.
1. Prospective vs. Retrospective Operation
A statute is prospective if it applies only to future transactions; it is retrospective if it takes away or impairs vested rights acquired under existing laws, or creates new obligations for past events.
| Substantive Law (Rights/Duties) | Procedural Law (Machinery/Courts) |
|---|---|
| Deals with vested rights, offenses, liabilities, and tax burdens. | Deals with court processes, rules of evidence, filing limits, and appeals. |
| Presumed to be strictly prospective in operation unless the legislature explicitly declares it retrospective. | Presumed to be retrospective in operation, applying to all pending suits, unless specified otherwise. |
2. Key Statutory Presumptions
When construing an Act, courts start with these default legal assumptions, which remain active unless rebutted by express words:
- Presumption of Constitutionality: The legislature is presumed to know the limits of its powers. Therefore, the court must assume the Act is constitutional and make every effort to uphold it.
- Presumption Against Ouster of Jurisdiction: Parliament is presumed not to exclude the jurisdiction of civil courts. Any clause excluding court review must be worded with absolute clarity.
- Presumption Against Retrospective Effect: Substantive statutes are presumed not to alter past transactions or destroy vested rights.
- Presumption Against Delegation: The legislature is presumed to exercise its own legislative power, prohibiting sub-delegation without express authority.