In McKesson Corp. v. Florida Alcohol & Tobacco Div. (1990) 496 U.S. 18, the United States Supreme Court addressed the question of the remedy due a taxpayer who challenges the constitutionality of a state tax. There, a wholesale liquor distributor challenged Florida's liquor excise tax as contravening the commerce clause. The preferential tax gave special rate reductions for certain products commonly grown in Florida and used in alcoholic beverages produced there. The manufacturer paid the taxes, applied for a refund, and when that was denied, sought declaratory and injunctive relief and a refund of excess taxes paid. The court framed the question as "whether prospective relief, by itself, exhausts the requirements of federal law." (McKesson, supra, 496 U.S. at p. 31.) The answer was a resounding "no." "If a State places a taxpayer under duress promptly to pay a tax when due and relegates him to a postpayment refund action in which he can challenge the tax's legality, the Due Process Clause of the Fourteenth Amendment obligates the State to provide meaningful backward-looking relief to rectify any unconstitutional deprivation." (McKesson, supra, at p. 31, ) This response stemmed from previous cases establishing the rule that because exaction of a tax amounts to a deprivation of property, "the State must provide procedural safeguards against unlawful exactions in order to satisfy the commands of the Due Process Clause." (Id. at p. 36.) The court went to lengths to underscore that Florida did not provide taxpayers like McKesson with any meaningful opportunity to withhold contested tax assessments and challenge their validity in a predeprivation hearing. The availability of such a hearing would constitute a procedural safeguard against unlawful deprivation sufficient to satisfy federal due process concerns. (McKesson, supra, 496 U.S. at pp. 36-39 & fn. 21.) Instead, the state had devised a variety of sanctions and summary remedies such that the liquor distributors would tender payments before their objections were addressed and resolved. Payments tendered under such schemes are deemed paid under duress because they are made to avoid financial sanctions or seizure of property. (Id. at p. 38, fn. 21.) What, then, is "meaningful backward-looking" relief ? When, as was the case in Florida, the state requires taxpayers to object to the tax in a postdeprivation refund suit, the state must give taxpayers both a "fair opportunity to challenge the accuracy and legal validity of their tax obligation" (McKesson, supra, 496 U.S. at p. 39, ), as well as a " 'clear and certain remedy' " for the erroneous or unlawful tax collection (ibid.). Moreover, this duty to provide a " 'clear and certain remedy' " requires a state to make sure that the tax as ultimately actually imposed on the complaining taxpayer and its competitors during the contested tax period does not deprive the taxpayer of tax money in a way that discriminates against interstate commerce. (Id. at p. 43.) Refunding the difference between the tax McKesson paid and the tax it would have paid had it enjoyed favored rate reductions of course would constitute meaningful retrospective relief. Alternatively, consistent with constitutional limitations on retroactive assessments, Florida might assess and collect back taxes from McKesson's competitors who profited from the rate reductions during the periods in question. This approach would, in hindsight, erase the discriminatory effects of the tax scheme. (Id. at p. 40.) And finally, the state could devise a hybrid solution, partially refunding to taxpayers in the petitioner's shoes, and levying a partial retroactive tax on the favored competitors, "so long as the resultant tax actually assessed during the contested tax period reflects a scheme that does not discriminate against interstate commerce ... ." (Id. at pp. 40-41.) The Supreme Court made it clear that when the tax scheme is pronounced unconstitutional because it discriminates against interstate commerce, the taxing entity "retains flexibility in responding to this determination" and may reformulate and enforce the tax during the contested tax period "in any way that treats the taxpayer and its competitors in a manner consistent with the dictates of the Commerce Clause. Having done so, the taxing entity may retain the tax appropriately levied upon the taxpayer pursuant to this reformulated scheme because this retention would deprive the taxpayer of its property pursuant to a tax scheme that is valid under the Commerce Clause." (McKesson, supra, 496 U.S. at pp. 39-40.) Remanding the cause to the Florida Supreme Court for further proceedings, the court underscored that the state was free to fashion an appropriate remedy consistent with the minimum due process requirements articulated in its decision. (McKesson, supra, 496 U.S. at pp. 51-52.)