By BridgeNews and Traci Purdum The U.S. Supreme Court announced it would not hear a challenge brought by five major oil companies against a clean gasoline patent owned by Unocal Corp., an El Segundo, Calif.-based oil and gas exploration and production company. In response, Unocal says the court decision reaffirms its "393" patent, adding that it was willing to license its patents for cleaner burning gasoline. "We believe that our patented formulations provide refiners and blenders with a cost-effective way of meeting California and federal standards for cleaner burning gasolines," says Charles R. Williamson, Unocal CEO. "We estimate that licenses for our patents would add less than 1 cent per gallon to the cost of reformulated gasolines nationwide." The Supreme Court's decision ends nearly six years of litigation between Unocal and major oil companies.