Thanks for your inquiry. Were you on FMLA when the termination occurred? If so, that is a violation of FMLA. Also, you may have appellate rights via the union, which sounds like you are currently exercising. Arizona is an "at will" state which means generally you can be fired for any reason unless the termination violates Federal or state law. Generally, employment lawyers charge a consult fee, and then sometimes require a retainer up front. This is typical of the industry. Thanks again for your inquiry.
Your union may be able to effectively challenge your termination and, if so, that is your first resort. It is typical for the employer to require a waiver of claims if there is an agreement for restoration of employment and consequential payment of back wages and benefits.
The FMLA issue may be productive -- the other two grounds you cite are less likely to be useful to you. Very likely you are not the only "active union member." If the others are not being discriminated against, that evidence tends to undermine any contention that is the basis for unlawful discrimination against you.
You have not identified the factual basis underlying your compliant against the manager for "harassing" you. But complaints for harassment are protected activity (i.e., insulation from employer action) only if the complaint pertains to certain kinds of harassment -- that based on race, religion, age, etc. -- the "protected" classifications. Complaints about harassment that is limited to abusive conduct, rudeness, and disrespect in the workplace are not protected.
Bear in mind that in most instances the employer is not required to demonstrate "a valid reason" for the termination. More often the employer is required only to demonstrate that the decision was not based on a prohibited bases. The distinction can be critical. Talk at length with your union rep and consult a local employment attorney for a fuller analysis of your facts and issues.
My responses to questions on Avvo are never intended as legal advice and must not be relied upon as legal advice. I give legal advice only in the course of an attorney-client relationship. Exchange of information through Avvo's Questions forum does not establish an attorney-client relationship with me. That relationship is established only by individual consultation and execution of a written agreement for legal services.
If you have a discrimination theory about retaliatory discharge or hostile workplace conditions you'll need a lawyer. Religious belief, age, gender, race etc. all are discriminatory reasons for which you cannot be legally fired and upon which you might base a wrongful termination suit.
If you are an at-will employee, you can be fired for any reason or no reason, except unlawful discrimination. If you do not have an employment contract or union to represent you, your recourse is limited. Discrimination based on age, gender, race, religious beliefs etc.... may give rise to a different answer.
You might find my Legal Guide helpful "Workplace Discrimination: A Basis for Wrongful Termination Claims"
Contact Mr. Fendon.