Legal Question in Business Law in California

Possibly, depending on what this person did and said, and the persons intent. There is a cause of action called, Intentional Interference with Prospective Economic Advantage that may apply.

It would also depend on whether you could prove damages as a result of what this other person did. Intentional Interference claims are not easy to prove.

You need to meet with a lawyer to discuss the situation in detail, and to see what remedies you might have.

I'd say "perhaps to probably." Tort law has a set of well-known theories upon which someone in your position can sue for money damages. Think of "slander," "libel," "malicious interference with prospective economic advantage" and a couple others. However, each of these causes of action has defenses. Your lawyer and you would need to discuss, among other things, the extent to which the damaging communications can be proven to have been made, whether and to what extent they are true, whether the person acted with legal malice or was legitimately making a warning, and whether the communications were subect to what is called "privilege," meaning that for policy reasons the maker was entited to make the statements. If you'd like a more accurate and detailed analysis (without cost or obligation) feel free to contact me directly with details.

That depends on what they said and under what circumstances. Your question does not provide enough facts to give you a better answer than that. You should discuss your situation in more detail with an attorney. Feel free to contact me directly if you want to.

Mr. Hoffman's answer is exactly correct. Any of the answers that seem to tell you more, are pure puffery. Rights to sue depend on facts, sometimes very detailed facts. Anyone who tries to tell you that you have a cause of action based on a question as vague and general as yours is just not being honest with you.