The legislation introduced in 1978 is the first stage of an intergovernmental cooperative scheme designed to apportion responsibility for the offshore areas between the Comonwealth and the States. It invests in the States authority over the territorial sea which they were widely supposed to possess before the decision of the High Court in New South Wales v. Commonwealth. In that case, the Court held that the territory of the States ends at the low water mark, with the consequence that the operation of State legislation beyond that point is extraterritorial and depends for its validity on an adequate connection with the peace, order, and good government of the State itself. The crimes at sea legislation of 1978 and 1979 extends the criminal laws of a State to the territorial sea bed or to crimes committed at sea with which the State is connected. The division of responsibility adopted for the enactment of these provisions is based on the premise that State power extends to offenses committed in the coastal sea or on an Australian ship during a voyage between places in the State. The most serious cause for concern as to the validity of this legislation lies in the possibility that it is repugnant to the Admiralty Offenses (Colonial) Act 1849 or the Territorial Waters Jurisdiction Act of 1878. The currently accepted interpretation of these statutes is that they confer on State courts jurisdiction over to offenses at sea to be exercised according to the law of England. The extension to the territorial sea of State law provides a greater risk of repugnancy to Imperial legislation than would an extension for a more limited local purpose. Footnotes are provided.