States can no longer block the free flow of wine through interstate commerce. Granholm v. Heald, No. 03-1116 (U.S. May 16, 2005).
Here's the holding:
States have broad power to regulate liquor under §2 of the Twenty-first Amendment. This power, however, does not allow States to ban, or severely limit, the direct shipment of out-of-state wine while simultaneously authorizing direct shipment by in-state producers. If a State chooses to allow direct shipment of wine, it must do so on evenhanded terms. Without demonstrating the need for discrimination, New York and Michigan have enacted regulations that disadvantage out-of-state wine producers. Under our Commerce Clause jurisprudence, these regulations cannot stand.
Slip op. at 35.