In the case of EEOC v. The GEO Group, Inc., No.:09-3093 (8/2/2010) , the Third Circuit Court of Appeals held that a uniform policy mandated in the George W. Hill Correctional Facility in Delaware County, PA, which prohibits prison guards from wearing Muslim head coverings, called khimars, in the prison did not constitute religious discrimination under Title VII.
Relying upon its previous decision in Webb v. City of Philadelphia, 562 F.3d 256 (3d. Cir. 2009), the Court deferred to the arguments made by the prison that allowing any headwear to be worn by prison guards, including khimars, would constitute a substantial security risk to individuals in the prison and that any policy allowing such headwear to be worn but switched or checked at various security checkpoints, would be implausible and time consuming. The Court noted that with respect to decisions involving security and safety, it would "not substitute our judgment for that of correction facility officials." As such, the Court held that the prison's ban on all religious headwear in this instance did not constitute religious discrimination under Title VII.
You can read the full text of the Court's opinion by clicking here: http://www.ca3.uscourts.gov/opinarch/093093p.pdf