Employers can impose qualification standards intended to exclude individuals with a disability that pose a direct threat (either health or safety) to themself or others if a reasonable accommodation can not be found. A direct threat is a significant risk of substantial harm. Before asking medical questions or arranging for a medical examination, make sure that poor job performance is being caused by a disability. If job functions are not being performed correctly, the reason may not be medical and the problem should be handled in accordance with company performance policies.
You can not refuse to hire or fire an employee because of a slightly increased or speculative risk of harm to himself or others. Under the ADA employers must make individualized decisions based on factual evidence, not assumptions or generalizations, ignorance, fear, patronizing attitudes, or stereotypes. By doing so the needs of the people with disabilities are balanced against the interests of employers in providing a safe workplace.
An employer should—
Do not base the decision on generalizations or unfounded fears. The harm must be serious and likely to occur and there must be no reasonable accommodation to reduce the risk.
29 C.F.R. § 1630.2(r)
Emergency Procedures under the ADA
The ADA does not prevent employers from obtaining and using employee medical information for an emergency evacuation plan. There are three different times an employer may obtain this information.
An employer can ask individuals to describe what kind of assistance is required in case of an evacuation. Employees should inform their employer if a special medication, equipment, or device is needed. Employees need only share information necessary for an emergency evacuation; in most cases it won't be necessary to share details about the employee's medical condition.
Information acquired for emergency purposes is kept confidential. The ADA allows that the information may be shared with first aid and safety personnel. In the case of an emergency evacuation plan, the information should be shared with anyone who needs the information to fulfill their responsibilities under the plan.