Effective Regulation of Public Utilities
Judicial review of the Commission's orders will ... function accurately and efficaciously only if the Commission indicates fully and carefully the methods by which, and the purposes for which, it has chosen to act, as well as its assessment of the consequences of its order for the character and future development of the industry.
Permian Basin Area Rate Cases, 390 U.S. 747, 791-92 (1968)