If you receive an EEOC or PHRC complaint, don't jump the gun to answer the charges. Carefully inspect the documents. If you don't question obvious problems now, such as lack of a verified signature, you lose the right to raise that issue later.
That can mean the difference between having a case tossed early on and going to trial.
Recent case: School secretary Kathleen Buck filed a harassment complaint with the EEOC. She failed to sign the complaint under oath, as required. But the school district responded anyway. The EEOC dismissed the case as frivolous, but Buck still sued in federal court.
The district tried to have the case tossed because of Buck's signature error. But the 3rd Circuit refused to dismiss the case, saying that since employers went ahead and answered the complaint, they lost the right to claim protection later. (Buck v. Hampton Township School District, No. 05-2373, 2006)
Final tip: Check every discrimination complaint to be sure it was signed under oath. If not, refuse to answer until it's verified.