Can we fire an employee who has gaven us false Dr. Statements to put himself off from work

Tennessee is what is called an employment at will state. Under the “employment at will” doctrine, both the employer and the employee are generally permitted, with certain exceptions, to terminate the employment relationship at any time for good cause, bad cause, or no cause. You can not fire the employee if it is based upon the employees race, sex, age, religious beliefs, national origin or as discrimination for the employee attempting to exercise a statutory or constitutional right, or for any other reason which violates a clear public policy which is evidenced by an unambiguous constitutional, statutory, or regulatory provision.