Sometimes, you have to trust that your lawyer and the courts will do the right thing and toss out a clearly frivolous case. As long as you are sure that you have solid reasons for firing an employee who wasn’t doing her job—and that you didn’t treat her any differently than any other employee with the same track record—fire her.
Usually, the courts will make quick work of the case and toss it out before extensive discovery.
Recent case: Dana Martin was fired for and refused to accept a severance package. Martin had absolutely no facts to back up her discrimination claims—all she could argue was that she “believed” she had been discriminated against on account of her sex. That didn’t cut it, and the court dismissed her case. (Martin v. Griffin Industries, No. 08-60306, 5th Cir., 2008)