IRS Publication 529 at https://www.irs.gov/pub/irs-pdf/p529.pdf on page 5 states:
You can deduct legal fees related to doing or keeping your job.
So I'm unclear myself if this is actually deductible. You didn't sue to keep your job, or to do your job. The job was already done, and you sued to get paid for doing it. You should talk with a tax attorney (not a CPA) in your state on this. I myself say you should be able to deduct it. But by my reading of pub 529, the "letter of the law" says you can't. I hope you can.