CA is an at-will employment state meaning employee can be fired for any reason or no reason, just not for illegal discrimination. Moral of story is if you get into an argument with boss you can be fired and have no legal basis to sue.
Your friend should file for unemployment and see if they can get it.
The response given is not intended to create, nor does it create an ongoing duty to respond to questions. The response does not form an attorney-client relationship, nor is it intended to be anything other than the educated opinion of the author. It should not be relied upon as legal advice. The response given is based upon the limited facts provided by the person asking the question. To the extent additional or different facts exist, the response might possibly change. Attorney is licensed to practice law only in the State of California. Responses are based solely on California law unless stated otherwise.
In California, the employment relationship is presumed to be at-will which means that you or your employer may terminate the relationship at any time, with or without cause. Nevertheless, employers may not discriminate or harass based on a "protected class" (i.e. race, national origin, age over 40, gender, sexual orientation, disability, religion). Employers also may not terminate an employee if it violates public policy (i.e. terminating an employee who complained about paychecks being late). An employer is not required to give a warning prior to terminating an employee.