That's already illegal. Even if you can somehow prove in court that "white worker X" would still be fired had he been black (already a dicey and likely impossible feat), just the fact that the employer already admitted that this worker was under more risk for getting fired due to his race, a-priory creates a cause of action against the employer.
If I say "I give preference to hiring men over women", and a woman is rejected and then sues, trying to show that I would not have hired her even if she was a man is arguing from a losing position.
The policy itself is racist and illegal.
what does 'carried out through a lens' mean. Through means it was put through that lens?