An Illinois coal company alleged that a Kentucky statute (SB 257) violated the dormant commerce clause — a constitutional doctrine denigrated as “famously complex,” “byzantine,” “inherently unpredictable” and “hopelessly confused.” Another Kentucky law says local utilities have to buy the cheapest coal. But Kentucky also has a severance tax on coal extraction. And Illinois — like many other coal-producing states — doesn’t. This “makes Kentucky utilities less likely to buy Kentucky coal,” Circuit Judge Joan L. Larsen …