I was recently terminated for misconduct, but I can prove that there was no misconduct on my part. Do I have a case?

Winning an unemployment appeal has absolutely nothing to do with having a basis for a wrongful termination lawsuit. To be eligible for unemployment you merely have to show that you either did not voluntarily quit your job or you were not fired for misconduct. The burden is on the employer to prove you were fired for misconduct. If the employer fails to prove this, you win and get unemployment. However, those findings are not relevant nor admissible in a civil court case for wrongful termination. Conversely, to prove wrongful termination, the burden is on you to prove you were fired for an unlawful reason, assuming you did not have a contract making you an exception to the at-will law. If you were an at-will employee, the employer does not have to prove it fired you for misconduct or even that it had a good reason to fire you. They can simply say they did not like you and that is sufficient. The question will boil down to, why do you believe the employer really fired you? If the true motive is one that is prohibited by law, and you can prove it, you have a case for wrongful termination. Simply proving you were not fired for misconduct is not enough. I won't attempt to speculate why your former employer is fighting to keep you from getting unemployment. Who knows what motivates people to do things that seem to make no sense?

First, I read your question as inquiring as to whether you have a right to bring a lawsuit for wrongful discharge or the like, not as inquiring about unemployment benefits. There are very limited circumstances in which a lawsuit may be brought after an employee is fired. First, was there a written employment agreement (such as a collective bargaining agreement)? If not, Were you discriminated against based on such factors as sex, pregnancy, age, disability, national origin, color, creed, race, or religion? If not, Did your employer engage in retaliation against you either after you were a "whistleblower" or after you opposed certain unlawful employment practices? If not, Did the firing violate any of your employer's written policies, such as those included in an employee handbook (which, in some states, are deemed to be contractual). If the answer to all of these questions is "no," then you have no lawsuit available to you. Good luck to you.

In California, employees are presumed to be "at will." At-will employees may be terminated for any reason, so long as it's not illegal. If you have an employment contract (like in a union setting) that provides that termination must be for just cause, you might have some right to show that the employer made a mistake. But since you don't mention that, I suspect it is not the case. Absent a contract, it doesn't matter if the employer is wrong about believing the misconduct. The only exception to that is if you were really fired for an impermissible reason (for instance, discrimination based on race, religion, sex, age). Again, you don't mention anything like that. In terms of thinking that the employer is "afraid of something" because they're fighting you on unemployment, there's really nothing to support that assumption. Some employers just don't like the thought of paying unemployment to employees who were fired. You mention retaliation, but retaliation would only come into play if you were engaged in an act that's protected by law. More facts would be needed to make that determination. If they just fired you because you had a hard time with management, that's not retaliation -- instead, that could support their termination decision if your "hard time" with them amounted to insubordination.