http://eeoc.gov/policy/docs/qanda_religion.html
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8. Does an employer have to grant every request for accommodation of a religious belief or practice?
No. Title VII requires employers to accommodate only those religious beliefs that are religious and sincerely held, and that can be accommodated without an undue hardship. Although there is usually no reason to question whether the practice at issue is religious or sincerely held, if the employer has a bona fide doubt about the basis for the accommodation request, it is entitled to make a limited inquiry into the facts and circumstances of the employees claim that the belief or practice at issue is religious and sincerely held, and gives rise to the need for the accommodation.
Factors that either alone or in combination might undermine an employees assertion that he sincerely holds the religious belief at issue include: whether the employee has behaved in a manner markedly inconsistent with the professed belief; whether the accommodation sought is a particularly desirable benefit that is likely to be sought for secular reasons; whether the timing of the request renders it suspect (e.g., it follows an earlier request by the employee for the same benefit for secular reasons); and whether the employer otherwise has reason to believe the accommodation is not sought for religious reasons.
However, none of these factors is dispositive. For example, although prior inconsistent conduct is relevant to the question of sincerity, an individuals beliefs or degree of adherence may change over time, and therefore an employees newly adopted or inconsistently observed religious practice may nevertheless be sincerely held. An employer also should not assume that an employee is insincere simply because some of his or her practices deviate from the commonly followed tenets of his or her religion.
9. When does an accommodation pose an undue hardship?
An accommodation would pose an undue hardship if it would cause more than de minimis cost on the operation of the employers business. Factors relevant to undue hardship may include the type of workplace, the nature of the employees duties, the identifiable cost of the accommodation in relation to the size and operating costs of the employer, and the number of employees who will in fact need a particular accommodation.
Costs to be considered include not only direct monetary costs but also the burden on the conduct of the employers business. For example, courts have found undue hardship where the accommodation diminishes efficiency in other jobs, infringes on other employees job rights or benefits, impairs workplace safety, or causes co-workers to carry the accommodated employees share of potentially hazardous or burdensome work. Whether the proposed accommodation conflicts with another law will also be considered.
To prove undue hardship, the employer will need to demonstrate how much cost or disruption a proposed accommodation would involve. An employer cannot rely on potential or hypothetical hardship when faced with a religious obligation that conflicts with scheduled work, but rather should rely on objective information. A mere assumption that many more people with the same religious practices as the individual being accommodated may also seek accommodation is not evidence of undue hardship.
If an employees proposed accommodation would pose an undue hardship, the employer should explore alternative accommodations.
10. Does an employer have to provide an accommodation that would violate a seniority system or collective bargaining agreement?
No. A proposed religious accommodation poses an undue hardship if it would deprive another employee of a job preference or other benefit guaranteed by a bona fide seniority system or collective bargaining agreement (CBA). Of course, the mere existence of a seniority system or CBA does not relieve the employer of the duty to attempt reasonable accommodation of its employees religious practices; the question is whether an accommodation can be provided without violating the seniority system or CBA. Often an employer can allow co-workers to volunteer to substitute or swap shifts as an accommodation to address a scheduling need without violating a seniority system or CBA.
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