Handling ADA accommodation requests is tricky, as you know. But the better prepared you are before you receive a request, the better your chances for staying on the right side of the law. 
To that end, employment law attorney Patti C. Perez of Ogletree Deakins suggests employers use this seven-point checklist to make sure they’re ready to engage in the ADA’s interactive process:
Define the process. Does your company have an easy-to-follow process for making accommodation requests? Tip: Have one person handle all requests.
Communicate. Begin a conversation with the employee as soon as he or she requests an accommodation, and document all interactions with him or her.
Gather employer documents. Compile relevant documents, like the employee’s job description, department expectations and performance evaluations. The more information you have, the easier it’ll be to create an accommodation plan.
Gather employee documents. Ask the employee for a detailed description of his or her restrictions. Keep the conversation on the restrictions – not on the medical condition itself.
Perform “match analysis.” Based on the employee’s restrictions, does a reasonable accommodation exist that would allow the person to continue to perform his or her job?
Explain your decision. Discuss the finer points of your final decision with the employee.
Follow up. Check in with the employee and managers after the accommodation is in place to make sure everything’s working.