The governing employment is of vast compass. Among the subjects it embraces are racial and sexual discrimination in employment, the liability of an employer (master) for the torts of his employees (servants), the regulation of occupational health and safety, employees' rights under the pension-regulation (ERISA), the emerging tort of wrongful discharge of an employee at will, and much else besides. But, to lawyers anyway, the most important subject in the of employment, as measured by the number of cases, the density of legal doctrine, and other measures of legal activity, remains-even in a period of union decline-the regulation by the National Labor Relations Board of the process by which unions seek to bargain collectively on behalf of workers.1 This regulation is conducted under the authority of the National Labor Relations Act,2 which is the Wagner Act of 1935,3 as amended, principally by the Taft-Hartley Act of 1947.4 When I use the term law in this paper, I shall, unless otherwise indicated, be referring to this regulatory scheme, even though properly speaking it is just a part of a much larger field. Whether defined broadly or, as I am doing, narrowly, labor is as natural a field for the application of economics to as one could imagine. It regulates explicit markets that have been a subject of continuous and fruitful economic study since Adam Smith's