Once an employee is on the job, an employer's right to conduct a medical examination is usually limited to so-called "fitness for duty" situations. If an employee exhibits objective indications that he or she is physically or mentally unfit to perform the essential functions of the job (for example, by claiming an injury that makes working impossible), an employer may request that the employee's fitness for the job be evaluated by a medical examiner.
Although the medical examiner can take a full history of the employee and conduct necessary tests to evaluate the employee's fitness, the employer is not generally entitled to all of this information -- only to the examiner's conclusions about whether the employee can work. Many states also impose strict limits on the information a doctor may disclose to an employer or an insurance company without the worker's consent.
Similarly, although an employer may request a medical certification from an employee who needs to take leave under the
Family and Medical Leave Act (FMLA), the employer is entitled only to specific information about the employee's need for leave -- not to a full health screening or medical history.
The law also imposes certain privacy protections for the results of a medical examination. Data gathered in medical examinations must be kept in a separate personnel file available only to those with a demonstrable need to know, such as supervisors -- who may need information about the employee's work restrictions or reasonable accommodations -- and first aid and safety personnel (if the employee's disability might require emergency treatment).
Information above and more can be found at
http://www.nolo.com/legal-encyclopedia/workplace-testing-employer-requirements-29496.html
