Walter B. Parker Act, which was signed into law in 1980 by U.S. President Jimmy Carter. On March 24, 1989, the Exxon Valdez oil tanker struck Bligh Reef in Prince William Sound, spilling an estimated 260,000 to 750,000 barrels of crude oil. The Exxon Valdez oil spill was a major environmental disaster for the state. Governor Steve Cowper, who held office at the time of the spill, appointed Walter Parker as the chairman of the Alaska Oil Spill Commission in 1989. The Alaska Oil Spill Commission was created by the Alaska state government to investigate the causes of the Exxon Valdez oil spill.
Oil tanker instrument, Shell consulted the "London Tanker Brokers’ Panel (LTBP)". At first, they divided the groups as "General Purpose" for tankers under ; "Medium Range" for ships between 25,000 and and "Large Range" for the then-enormous ships that were larger than . The ships became larger during the 1970s, which prompted rescaling. The system was developed for tax reasons as the tax authorities wanted evidence that the internal billing records were correct. Before the New York Mercantile Exchange started trading crude oil futures in 1983, it was difficult to determine the exact price of oil, which could change with every contract.