One form of illegal discrimination involves asking applicants or employees for medical information or requiring medical exams when not specifically allowed under the federal Americans with Disabilities Act (ADA).
The ADA has different provisions on this for applicants and employees.
Tests for illegal drug use are not considered medical exams, but alcohol tests are. If the question or exam is required by another federal law, the ADA provisions do not apply.
Applicants – post offer
After a job offer is made, employers may make medical inquiries or require medical exams only if they require such exams or inquiries for all entering employees in a particular job category.
Employers may not use such information to exclude an applicant with a disability on the basis of the disability, unless they can show that the exclusion is job related and consistent with business necessity and that legitimate job criteria cannot be met with reasonable accommodation.
Employees
Employers may request reasonable documentation when an employee requests an accommodation, as long as the condition or need is not obvious.
Otherwise, employers may make medical inquiries or require medical exams of employees only when they have a reasonable believe, based on objective evidence, that a particular employee is unable to perform the job’s essential functions because of a medical condition or the employee will pose a direct threat due to the medical condition.