What constitutes unfair trade from a former employer?

Long story short here, or at least less long than it could be.

After several years at a professional firm in Colorado, I resigned and started my own company (also in Colorado). I did not have a noncompete agreement, so that has never been an issue. My departure was markedly unfriendly, since I resigned in protest of a partner's unethical behavior.

I was recently informed that a major client is dropping me from its stable of professional firms. This client has a contracting history with my old firm (I brought the client into the firm and was the project manager) and with my new firm. I did not market to this client before or after I left my old employer - they called me to solicit my work many months after I started my new company.

Anyway, a friend who works for the client told me that her boss made a negative comment about why I left my old company, and gave orders to the staff to stop retaining my firm for projects and to start using my old company instead. She was afraid to tell me what the comment was.

I know that the unethical partner in the old firm has told at least one person that he fired me, and has done the same to another employee who resigned for the same reasons that I did.

My questions:

1. Is it illegal for him to claim that he fired me, or to state any false reason for my departure from the firm? This is obviously the reason that I lost a good client to him. If so, would the case be considered unfair competition, slander, or some employment-related issue? (I should note that I have said nothing to the client other than that I disapproved of his business practices.)

2. If it is illegal, what proof do I need to win in court? Would it be legal to set up a fake scenario with a fake client to give him the opportunity to speak into a microphone or provide written statements? Would that hold up in court? Could I set up a fake scenario with the client to ask for a project reference? Several people appear to be aware of my former employer's false comments, but no one will tell me what he's saying.

3. What sort of damages could I pursue? My former firm has made about $1.5 million in contracts with this client and a related client, and I have not been allowed to compete for the work, despite being more qualified.

4. Does anyone know a good Denver-area attorney that would handle this type of case?

I would appreciate any advice that anyone can offer.

[Edited by bizowner on 06-12-2001 at 01:03 PM]