The U.S. Supreme Court allowed the meat processing unit for Pleasanton-based Safeway Inc. to file an interstate lawsuit against a Jack-in-the-Box restaurant franchise over a deadly 1993 outbreak of food poisoning. The case stemmed from illnesses due to E. coli bacteria traced to hamburgers sold at Jack-in-the-Box restaurants in several Western states. Jack-in-the-Box is a division of San Diego-based Foodmaker Inc. Foodmaker blamed the contamination on its meat suppliers, including Safeway unit Vons Companies Inc., which processed hamburger patties for use in the restaurants. Eighty-five franchisees from California and other states whose customers did not become sick filed a suit in California against Foodmaker, Vons and other meat processors seeking damages for loss of business after the outbreak. Vons then filed its cross-complaint against Foodmaker and the owners of the franchise restaurants in Washington implicated in the outbreak. Vons said in its suit that the outbreak could have been avoided if Foodmaker and its franchise restaurants had cooked the hamburgers sufficiently.