Monica Lewinsky Scandal
Linda Tripp, a former White House worker, was convinced that Bill Clinton and Monica Lewinsky were having an affair. After confronting Lewinsky, her beliefs were confirmed. She began secretly recording phone calls between Clinton and Lewinsky, where Clinton tried to convince Lewinsky to lie in his ongoing Clinton v Jones case, which was unrelated to the Monica Lewinsky scandal. Tripp became friends with Lewinsky, and convinced her to not wash the semen off of her dress (proving Clinton was guilty) and also convinced her to not sign an affidavit denying her affair with Clinton.
Tripp leaked this information, mainly in audio tapes (which the legality was debated upon).
The America's Future Foundation stated:
Personally, I believe that personal scandal is not a good reason for the impeachment of a president, but lying to the nation and court is debatable. He says he was trying to protect his family, which may be admirable, but it was his fault for engaging in sexual involvement with Lewinsky.