Legal Question in Employment Law in California

It sure is. Employee conduct discipline not only legally can be, it rationally must be personal to the employee. An employee who's personal phone use is enough of a problem that they have to be told to leave their phone in their car or turn it over to their manager should be glad they still have a job. A great many firms would just let you go.

Yes, and it would be 'legal' for them to fire you any time for any reason, with or without �cause�, explanation or notice. Treat this as a wake up call about the attitude and effort you owe the employer. 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.