While the ADA entitles disabled employees to workplace accommodations, it's important to recognize that health and safety always take the front seat.
Before granting requested accommodations, your first consideration must be the safety of co-workers, customers and disabled employees themselves.
If an employee's disability has caused an accident, it's OK to call a timeout and withhold that accommodation for a while. Then look for ways to bring the employee back safely. If you can document your good-faith efforts, the employee's disability discrimination claim won't go far.
Recent case: Vivian Clayborne has a progressive vision defect that is slowly blinding her. She worked as a mail-processing clerk for many years but, as her condition deteriorated, the Postal Service removed tasks that proved too difficult.
Finally, after a series of accidents caused by low vision, the Postal Service placed Clayborne on disability leave. For almost a year, it explored possible accommodations and finally purchased a powerful light and magnifying glass that allowed her to return to work.
She sued anyway, claiming a year was too long to wait. Not so, concluded the court. Because safety came first, and because the Postal Service was working toward an accommodation, the delay was justified. (Clayborne v. Potter, No. 05-915, DC DC, 2006)