How To Check Out A Doctor?

Hi all...I'm a little ashamed that I don't know the answer to this since I work in the legal field.
How do you check to see if a physician has had any disciplinary actions or malpractice claims for FREE? I certainly see alot of websites that offer reports for a fee but is there a site that offers this info. for no charge? Does it differ from state-to-state?
I want to check out an oncologist in Tennessee. Thanks in advance for any help you can provide!