Catherine Hantzis (plaintiff) was a full-time student at Harvard Law School and resided in Boston, Massachusetts. Hantzis secured a temporary summer job as a legal assistant in New York. While working in New York, Hantzis regularly traveled back to Boston to see her husband. On her federal tax return, Hantzis deducted her travel and living costs while in New York as a business expense pursuant to 26 U.S.C. § 162(a)(2). The federal tax commissioner (commissioner) (defendant) disallowed Hantzis’s business-expense deduction, determining that (1) Hantzis’s home for purposes of § 162(a)(2) was New York, her place of employment, such that her costs were not incurred while away from home; and (2) Hantzis’s costs were not incurred in pursuit of a trade or business. Hantzis petitioned the United States Tax Court for a redetermination. The tax court rejected both of the commissioner’s positions, holding that Boston was Hantzis’s home for purposes of § 162(a)(2) because her employment in New York was only temporary. The tax court entered judgment for Hantzis. The commissioner appealed to the United States Court of Appeals for the First Circuit.