You would need to show there is no reason for a disparity (experience, same type of work, etc.) and I think you would need to show it's systematic and/or intentional.

I know the someone getting scared thing, and you want an objective third party to show it isn't he said, she said and their reaction was unreasonable.

It's probably worth contacting the EEOC if you no longer work there. It's more of a cost benefit analysis if you still work there.

If you still work there and you think you may get fired soon, I always tell people to make a complaint before being fired. It makes it harder for them to fire you and/or you can claim whistleblower status protections.

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"Everyone has a plan until you punch them in the face. Then they don't have a plan anymore." (c) Mike Tyson

"what's a leader if he isn't reluctant"