I forgot to put the word legal before employers like I did upthread. I'm sorry if that changes your answer and you feel like you wasted your time, because basically what you wrote about illegal employment makes sense to me. Thanks for the thoughtful response.
Ah, if you put the word 'legal' there, then there is no discussion and nothing to talk about: legal is whatever it says in the law of your country. I'm not in USA, so I have no idea what is or isn't legal, and don't actually care. Legal has nothing to do with ethics and whether something is right or wrong, and doing something that is ethical but illegal is always preferred over something that is legal but unethical. It would always be an ethical imperative to attempt to change an unethical law as well.
Of coarse, sometimes we put our own safety above ethics, and people have differing opinions on whether that is right or not. There is no easy answer there.
I am surprised to hear that laws and ethics have nothing to do with each other. Is it a random chance that murder is illegal and unethical just about everywhere?
Really I was just wondering if you have any examples of legal but unethical employers that you believe it's okay for a university to cite to discriminate against an applicant, in your home country. Perhaps the military?