Legal Question in Employment Law in California

Re: My employer says that i cannot sing along with music at work

If you were singing political songs, that's one thing. However, there really isn't much freedom of speech (or song) in the workplace. A person's rights are restricted to a certain extent. For instance, the employer can install cameras to keep you under surveillance to see that you're doing your job. The employer also could watch whatever you're typing on the workplace computer. The employer could even rifle through stuff on your desk. Now, if your employer were a music school or the Grand Ole Opry, that would be a different story. Take care, and stay in tune.