Because of some apprehension as to the possible effect of sec. 55 of the Constitution on its validity, if the sales tax legislation were enacted in one assessment Act and one taxing Act, it was passed in the form of nine separate machinery statutes and nine separate taxing Acts. They constitute, however, a single legislative scheme to the complete operation of which all are necessary, and they should be construed together. Moreover, the legislation depends in a remarkable degree upon the regulations made under the power which it confers on the Executive. Without the regulations, not only is it unworkable, but the expression of legislative policy is so inadequate as almost to be unintelligible. Although the tax levied by the enactments is called a sales tax, it is not a tax upon all sales of commodities. It is a tax levied upon one only of the transactions which commonly take place in respect of goods before they reach the consumer after they are imported into or produced in Australia. It appears that it was not intended that the retail price of goods should be increased by the incorporation in it of more than one amount of tax. The general policy of the legislation is to levy this tax upon the last sale of the goods by wholesale, that is upon the sale to the retailer by the last wholesaler. To give effect to this policy, every person who engages, whether exclusively or not, in the sale of goods by wholesale is required to register. Upon registration, he becomes bound to keep proper books, make returns of his sales, and pay the tax. He receives a certificate bearing a number and this certificate he is bound to quote when he buys goods, unless, besides being a wholesale merchant, he is a retailer and he sells principally by retail. A sale to a person who quotes his certificate is not the subject of tax, and thus, if there be successive sales to wholesalers, the goods do not incur tax until the last wholesaler sells them to the retailer. Then an ad valorem duty is imposed on that sale, which presumably was considered likely to be at a price higher than the preceding sales. It was not the object of the legislation to levy the tax on sales by retail. But obviously the general policy of taxing the last sale by wholesale, the sale by a wholesaler to a retailer, did not admit of universal application. Manufacturers and importers might themselves sell by retail. Wholesale merchants, although they sold chiefly by wholesale and not principally by retail, owing to the exigencies of commerce might actually sell by retail goods which had been purchased with the intention of reselling them by wholesale. Manufacturers, importers, and wholesale merchants might take into their own consumption or use the goods they had acquired in the course of their businesses. Moreover, goods are introduced into Australia either by importation or manufacture, and until the tax is levied upon them, their course from that point towards consumption must be capable of check. Elaborate provisions are made in the Acts and regulations to deal with these matters.[1] Manufacturers must be registered and receive certificates. They must pay tax upon the first sale of manufactured goods, unless the buyer is himself registered and quotes his certificate. Manufacturers also must pay tax when they take their manufactured goods into use or consumption. The buyer from the manufacturer, if he is or ought to be registered, must pay tax when he sells, unless the buyer from him is registered and quotes his certificate, and he must pay tax if he takes into his own use or consumption the goods he has bought from the manufacturer. So with any subsequent buyer of goods manufactured in Australia, who resells the goods by wholesale, or who takes into his own use or consumption goods in respect of the purchase of which he quoted his certificate. The tax is levied on the actual sale price, if the sale be by wholesale. If it be by retail, a wholesale price ascertained by other means is adopted, and the tax is calculated upon that.