Reasons 1 & 2

Essential job functions are very important for a supervisor to understand in applying this law. You need to be able to distinguish essential from non-essential job functions.

Reasons for determining if a job function is essential?

1.    The position exists to perform this function. If the function is
        removed it would be a different job.

2. A limited number of employees is availabe to perform the function,
        or among whom the function can be distributed.

      Example: An office clerk in a busy three-person office must answer
       the phones. Due to the work volume, it is not possible to reassign
       this function to another a employee.