In Richfield Oil Corp. v. State Board of Equalization, 329 U.S. 69 (1946), the Supreme Court was concerned with when the "exportation" or "movement of a product abroad" began. The commencement thereof of the product for the foreign market makes the product an export. In Richfield Oil, the Court held that oil, the product at issue in that case, became an "export" at the time it was delivered into the hold of a sea-going vessel, at which time it passed into the control of a foreign customer, there being no probability that the oil would thereafter be diverted to domestic use. 329 U.S. at 83, 67 S. Ct. at 164. In Richfield Oil, California had assessed a retail sales tax against the seller/deliverer of the oil measured by the gross receipts from the transaction. The seller protested and sought a refund claiming that the levy of the tax violated the Import-Export Clause. As interpreted by the California Supreme Court, the California tax was described as an excise tax for the privilege of conducting a retail business measured by the gross receipts from sales. It was not a tax on the sale or because of the sale. While the United States Supreme Court in Richfield Oil said that it was bound by the California court's construction, being a matter of state law, the Supreme Court found that that determination was not determinative of the question of whether the tax deprived the taxpayer of a federal right, stating "that issue turns not on the characterization which the state has given the tax, but on its operation and effect". 329 U.S. at 84, 67 S. Ct. at 164. (Emphasis added.) The Supreme Court then made much of a concession by the California court, namely, "that the delivery of the oil 'resulted in the passage of title and the completion of the sale, and the taxable incident'". Id. (Emphasis added.) The Supreme Court's holding that the California tax was unconstitutional under the Import-Export Clause was based, in my opinion, on its conclusion that "the incident which gave rise to the accrual of the tax was a step in the export process". Id. In Richfield Oil Corp. v. State Board of Equalization, 329 U.S. 69 (1946), the State of California assessed a retail sales tax on a sale of oil by a California refinery to the government of New Zealand. The Supreme Court found that the California sales tax was imposed when the oil was delivered into the hold of the foreign purchaser's ship and into the control of a foreign purchaser; that the sales tax was therefore imposed on the oil while it was in the export transit process; and the tax was therefore an impost or duty that violated the Import-Export Clause. To support its conclusion, the Richfield Oil Court looked to language in two earlier cases: (1) Coe v. Errol, 116 U.S. 517 (1886) (goods became exports to which the Import-Export Clause automatically applied when they had "been started upon such export transportation in a continuous route or journey."); (2) A. G. Spalding & Bros. v. Edwards, 262 U.S. 66 (1923) (goods became exempt exports "after they had been loaded".)