Legal Question in Employment Law in California

In general, unless an employee is civil service, in a union, or has a written employment contract, they are an 'at will' employee that can be disciplined or fired any time for any reason, with or without ‘cause’, explanation or notice, unless it is based upon illegal discrimination, harassment or retaliation as defined under the ADA [disability], Civil Rights [age, race, sex, ethnic, religion, pregnancy, etc], FMLA [medical leave], Whistle-blower, or similar statutes. Any employee's goal should be to keep their supervisors happy and make them look good to the company, and make the company money. That’s how the company pays employee wages. If you don't, then don't be surprised to be replaced.