When first enacted, the Act codified the common law in some cases. For example, there is a presumption at common law that parliament intends its legislation to operate only on persons and matters within its territory. The Acts Interpretation Act 1901 (Cth) repeated that presumption at section 21(1)(b): if an act was silent on the question, then the provision operated to confine the act in its territorial reach. However, parliament may override the presumption and the section to give extraterritorial operation to the enactment by express words or "necessary implication".