During the Vietnam War, Justin Popa (plaintiff) was an American businessman based in Saigon, South Vietnam. In April 1975, Popa left Saigon on a business trip to Thailand. A day or two later, Saigon was suddenly overrun by enemy forces, and all United States citizens were evacuated. Popa was unable to return to Saigon and had no reasonable hope of ever recovering his Saigon property or its value. Popa claimed a casualty-loss tax deduction for his property loss. The commissioner of internal revenue (commissioner) (defendant) disallowed the deduction, determining that Popa’s loss was not a casualty loss as defined by § 165(c)(3) of the federal tax code. Popa filed a petition challenging the commissioner’s determination.