What is an "undue hardship"?

The duty to accommodate does not apply to an employer who can demonstrate that the accommodation would impose an undue hardship on the operation of its business.  Undue hardship is defined by the ADA as an action requiring significant difficulty or expense, in view of its nature and cost, the financial resources of the employer, the size of the business, number of employees, type of operation and facility, and a variety of other factors.  Undue hardship analysis is also circumstance specific.