What can I do regarding slander from a previous employer?

Question Details: I was having a background investigation done for a security clearance and the investigator asked me about substance abuse. I have never used illegal substances of any kind. The investigator told me that one of my previous employers stated that prior to employment there, I had a substance abuse problem but it wasn't a problem while I was working there. Again, I have never used illegal substances of any kind. They have no proof that I ever had a problem. I do not know where they got this information or why they said it. However, it has negatively affected my security clearance. What legal action can I take?

IMPORTANT NOTICE: The Answer(s) provided above are for general information only. The attorney providing the answer was not serving as the attorney for the person submitting the question or in any attorney-client relationship with such person. Laws may vary from state to state, and sometimes change. Tiny variations in the facts, or a fact not set forth in a question, often can change a legal outcome or an attorney's conclusion. Although AttorneyPages.com has verified the attorney was admitted to practice law in at least one jurisdiction, he or she may not be authorized to practice law in the jurisdiction referred to in the question, nor is he or she necessarily experienced in the area of the law involved. Unlike the information in the Answer(s) above, upon which you should NOT rely, for personal advice you can rely upon we suggest you go to AttorneyPages.com and retain an attorney to represent you.