Section 51(i) of the Constitution of Australia
Section 51(i) of the Australian Constitution enables the Parliament of Australia to make laws about: Trade and commerce with other countries, and among the States; The meaning of trade and commerce is clarified in section 98 of the Constitution which provides The power of the Parliament to make laws with respect to trade and commerce extends to navigation and shipping, and to railways the property of any State. == Interpretation by the courts == "Trade" and "commerce" have been broadly construed.
Source: Wikipedia — Section 51(i) of the Constitution of Australia (CC BY-SA 4.0)