An employer may not ask or require a job applicant to take a medical examination before making a job offer. It cannot make any pre-offer inquiry about a disability or the nature or severity of a disability. An employer may, however, ask questions about the ability to perform specific job functions and may, with certain limitations, ask an individual with a disability to describe or demonstrate how s/he would perform these functions.
An employer may condition a job offer on the satisfactory result of a post-offer medical examination or medical inquiry if this is required of all entering employees in the same job category. A post-offer examination or inquiry does not have to be job-related and consistent with business necessity.
However, if an individual is not hired because a post-offer medical examination or inquiry reveals a disability, the reason(s) for not hiring must be job-related and consistent with business necessity. The employer also must show that no reasonable accommodation was available that would enable the individual to perform the essential job functions, or that accommodation would impose an undue hardship. A post-offer medical examination may disqualify an individual if the employer can demonstrate that the individual would pose a "direct threat" in the workplace (i.e., a significant risk of substantial harm to the health or safety of the individual or others) that cannot be eliminated or reduced below the "direct threat" level through reasonable accommodation. Such a disqualification is job-related and consistent with business necessity. A post-offer medical examination may not disqualify an individual with a disability who is currently able to perform essential job functions because of speculation that the disability may cause a risk of future injury.
After a person starts work, a medical examination or inquiry of an employee must be job-related and consistent with business necessity. Employers may conduct employee medical examinations where there is evidence of a job performance or safety problem that they reasonably believe is caused by a medical condition, examinations required by other federal laws, return-to-work examinations when they reasonably believe that an employee will be unable to do his job or may pose a direct threat because of a medical condition, and voluntary examinations that are part of employee health programs.
Information from all medical examinations and inquiries must be kept apart from general personnel files as a separate, confidential medical record, available only under limited conditions.
Tests for illegal use of drugs are not medical examinations under the ADA and are not subject to the restrictions of such examinations.
For additional information, take a look at the following resources:
FAQ: What are my employer's obligations after I return from medical leave? (What kind of documentation can the employer ask for when I return from medical leave?)
FAQ: Who is a “qualified individual”?
FAQ: Does the ADA require that an applicant or employee with a disability be qualified for the position?