Can I be fired from my job for self defense?

Maybe. It's tough to say for sure. Any time you have a situation where an employee is not following a manager's instruction the manager should follow the procedure in the employer's handbook or employee policies. Often that involves a verbal or written notice, suspension, possibly termination. If you verbally warned the employee, maybe writing them up would have been the next step. Most employers are not excited about calling the police unless it looks like safety is an issue. A guess would be that this employee might have a history of being problematic. Some employees need to be removed or suspended when it looks like they might get out of control. It's hard to say whether you should have called the police first. The employer may allege that you did not follow its policies or the handbook. It looks like you may have acted reasonably but that might not support discrimination. You know the hardest part of our jobs? Tellling employees that: 1) If they have no written employment agreement like a union contract or a private employment contract AND 2) The terminated employee has no facts to support a plausible (not just a guess or a hunch) theory of discrimination, unless is unpaid wages, we often cannot help. Courts are not super personnel boards. That means that a court will not come in and tell a poorly managed company how to run its business. Sometimes a company has no idea who was at fault and it just fires everyone. That's not necessarily illegal unless an employee has evidence of some form of discrimination against recovering addicts, persons with disabiliites, or other protected classes of employees. You should recover unemployment benefits unless you committed gross misconduct. If you touched the employee first, even if he taunted you to do so, that might be gross misconduct and benefits recovery questionable. Keep looking for another job. All employees have duties to mitigate or find new work and you are in an industry that needs skilled managers and employees.