Mass firings at meatpacking plants in Colorado and Nebraska last month highlight growing conflicts over how to accommodate religion in the workplace.
The plants, owned by the U.S. unit of Brazil's JBS SA, collectively fired about 200 Muslim Somali workers who walked off the job over prayer disputes.
The workers had asked management to adjust their evening break times so they could pray at sunset. Managers at both plants initially agreed but then reversed their decisions after protests by non-Muslim workers.
The tension in the JBS plants comes amid a surge in workplace disputes over religion. Claims of religious discrimination filed with federal, state and local agencies have doubled over the past 15 years and rose 15% during 2007 to 4,515, a record.