Since the Americans with Disabilities Act was passed in 1991, employers have come to appreciate the significance of the term "essential job functions." Those are the functions that a person claiming to be disabled must be able to perform despite his or her disability, so long as the employer offers a reasonable accommodation.

Under new ADA rules, employers should not apply attendance rules to terminate the employment of a disabled employee without first allowing additional leave if the extra time would enable the employee to return to work and would not unduly burden the organization. These are difficult determinations, yet another HR obligation.

Since the Americans with Disabilities Act was passed in 1991, employers have come to appreciate the significance of the term "essential job functions." Those are the functions that a person claiming to be disabled must be able to perform despite his or her disability, so long as the employer offers a reasonable accommodation.

Identifying those functions, then, only leads to the second question: what constitutes "reasonable accommodation"? Employers have learned that the answer depends on many factors that vary widely according to the individual and the workplace.

One relative constant in the world of ADA uncertainties has been that a disabled individual must nonetheless meet attendance requirements. Courts have routinely held that being at work is an essential job function. They have also generally ruled that reasonable accommodation obligations do not mean an employer must excuse an employee from attendance rules.

No longer. Following the ADA amendments of 2008 and the EEOC's implementation of new regulations this spring, attendance remains an essential job function, but bending attendance rules is now required as part of reasonable accommodation.

Thus, if an employee has a disability and, as a result, needs time away from work beyond what is offered under the Family and Medical Leave Act or the employer's regular policies, the employer may not automatically discharge the employee for missing work. When all available leave has expired, an employer must instead evaluate on a case-by-case basis how much additional time a disabled employee needs to return to work and how that delay would impact the organization.

The ADA gives no firm rules on how much extra time–off is necessary, leaving it to employers to make their best judgment in each new circumstance and to hope that the EEOC or a court does not later disagree. Erring on the side of caution is advisable, because resulting litigation can be dangerous when a sympathetic individual portrays his former employer as inflexible.