In United States v. American Bar Endowment, 477 U.S. 105, 106 S.Ct. 2426, 91 L.Ed.2d 89 (1986), the Supreme Court considered the question of the extent to which payments to organizations that bear the "dual character" of a purchase and a contribution are deductible under 170. 477 U.S. at 116-18, 106 S.Ct. 2426. IRS Revenue Ruling 672-46 had set forth a two-part test for determining the extent to which such payments are deductible: First, the payment is deductible only if and to the extent it exceeds the market value of the benefit received. Second, the excess payment must be "made with the intention of making a gift." Id. at 117, 106 S.Ct. 2426 (quoting Rev. Rul. 67-246, 1967-2 Cum. Bull. 104, 105 (1967)). The Court held that Revenue Ruling 67-246 embodied the proper standard, reasoning: "The sine qua non of a charitable contribution is a transfer of money or property without adequate consideration. The taxpayer, therefore, must at a minimum demonstrate that he purposely contributed money or property in excess of the value of any benefit he received in return." Id. at 118, 106 S.Ct. 2426. In American Bar Endowment, taxpayer members of a charitable organization sought to deduct under 170 refunds from insurance policies negotiated and purchased on their behalf by the charitable organization, which they donated to the organization. See id. at 106-09, 116-18, 106 S.Ct. 2426. They claimed that the premiums paid for the insurance, part of which was subsequently refunded due to the "experience rating" of the policies, were dual payments. Id. The Supreme Court held that the taxpayer members met neither prong of the two-part test for deductibility of dual payments. Stating that the "most logical test of the value of the insurance the benefit received in return for their payment is the cost of similar policies," the Court held that because three of the four taxpayers "failed to demonstrate that they could have purchased similar policies for a lower cost," they failed to demonstrate that their payment exceeded the market value of the benefit received. Id. at 118, 106 S.Ct. 2426. Because the fourth taxpayer, who did prove that there was a comparable insurance program at a lower premium rate for which he was eligible, failed to demonstrate that he knew about the available lower premium during the tax years at issue, the Court held that he failed the second prong of the test - "that he intentionally gave away more than he received." Id.