Double-hulled tanker after 6 July 1993 to be fitted with double hulls, or an alternative design approved by IMO". However, in the aftermath of the Erika incident of the coast off France in December 1999, members of IMO adopted a revised schedule for the phase-out of single-hull tankers, which came into effect on 1 September 2003, with further amendments validated on 5 April 2005. After the Exxon Valdez oil spill disaster, when that ship grounded on Bligh Reef outside the port of Valdez, Alaska in 1989, the US Government required all new oil tankers built for use between US ports to be
Exxon Valdez oil spill effectively a bill of attainder, a regulation that was unfairly directed at Exxon alone. In 2002, the 9th Circuit Court of Appeals ruled against Exxon. As of 2002, OPA had prevented 18 ships from entering Prince William Sound. OPA also set a schedule for the gradual phase in of a double hull design, providing an additional layer between the oil tanks and the ocean. While a double hull would likely not have prevented the "Valdez" disaster, a Coast Guard study estimated that it would have cut the amount of oil spilled by 60 percent. The "Exxon Valdez" supertanker was towed