Opinion of the Court
“to accede to or accommodate” religious practice because that “would raise grave” Establishment Clause questions. Dewey v. Reynolds Metals Co., 429 F. 2d 324, 334. This Court granted certiorari, 400 U. S. 1008, but then affirmed by an evenly divided vote, 402 U. S. 689 (1971).
Responding to Dewey and another decision rejecting any duty to accommodate an employee’s observance of the Sabbath, Congress amended Title VII in 1972. Hardison, 432 U. S., at 73–74; id., at 88–89 (Marshall, J., dissenting). Tracking the EEOC’s regulatory language, Congress provided that “[t]he term ‘religion’ includes all aspects of religious observance and practice, as well as belief, unless an employer demonstrates that he is unable to reasonably accommodate to an employee’s or prospective employee’s religious observance or practice without undue hardship on the conduct of the employer’s business.” 42 U. S. C. §2000e(j) (1970 ed., Supp. II).
B
The Hardison case concerned a dispute that arose during the interval between the issuance of the EEOC’s ”undue hardship” regulation and the 1972 amendment to Title VII. In 1967, Larry Hardison was hired as a clerk at the Stores Department in the Kansas City base of Trans World Airlines (TWA). The Stores Department was responsible for providing parts needed to repair and maintain aircraft. Hardison v. Trans World Airlines, 375 F. Supp. 877, 889 (WD Mo. 1974). It played an “essential role” and operated “24 hours per day, 365 days per year.” Hardison, 432 U. S., at 66. After taking this job, Hardison underwent a religious conversion. He began to observe the Sabbath by absenting himself from work from sunset on Friday to sunset on Saturday, and this conflicted with his work schedule. The problem was solved for a time when Hardison, who worked in Building 1, switched to the night shift, but it resurfaced when he sought and obtained a transfer to the day shift in
