In law school, Paul Wassenaar (plaintiff) was paid for researching, editing, and writing law-review articles. Wassenaar also was paid for assisting a law firm with legal drafting and client consultation. Wassenaar graduated from law school in June 1972 and began studying for the bar examination and looking for employment as a lawyer. In September 1972, Wassenaar entered New York University (NYU) to study for a master’s degree in taxation. Wassenaar graduated from NYU in May 1973. Wassenaar was admitted to the bar shortly thereafter, and launched a law practice in the summer of 1973. Wassenaar deducted the cost of his NYU education as a tax-deductible employee business expense under § 162(a) of the federal tax code. The commissioner of internal revenue (commissioner) (defendant) disallowed the deduction because Wassenaar’s NYU costs were not ordinary and necessary expenses of Wassenaar’s trade or business. Wassenaar filed a petition challenging the commissioner’s decision.