IANAL but my understanding is that many employers either understand themselves to be required to, or for some other reason the corporation requires it and the d

IANAL but my understanding is that many employers either understand themselves to be required to, or for some other reason the corporation requires it and the department which is hiring does the same thing described, albeit in this case to satisfy internal rules rather than external laws. But clearly this all varies by nation, state, city, industry, etc.