The Interstate Commerce Commission (ICC) (defendant) regulated the rates that railroads could charge for the interstate shipments of goods and commerce. Arkansas Power & Light Co. and other coal burning utilities (plaintiffs) petitioned the ICC to institute rulemaking to collect data to enable the agency to implement its responsibilities for approving the rates railroads may charge to “captive” shippers. The ICC rejected the petition for rulemaking, concluding that the collection of such data would be unnecessarily burdensome and that it would be more productive and efficient to develop standards on a case-by-case basis. In reaching this decision, the ICC also indicated that it would follow adequate procedures in individual adjudications to enable petitioners to obtain the type of data that they were seeking through rulemaking. The plaintiffs sought review of the ICC’s decision.