CentiMark Corporation, a large commercial roofing company, was working on a roof replacement project in Pittsburgh, Pennsylvania, when a compliance officer from the Occupational Safety and Health Administration observed a CentiMark employee on the roof without fall protection. After conducting an inspection, OSHA issued CentiMark a one-item citation alleging a repeat violation of 29 C.F.R. § 1926.501(b)(10), which requires employees “engaged in roofing activities on low-slope roofs” to be protected from falling by one of several enumerated methods.