He became a public figure when a friend of his, Congressman Henry Hyde, asked him to be the Chief Investigative Counsel for the US House Judiciary Committee, which was holding an inquiry on whether President Bill Clinton had committed impeachable offenses in his handling of the Paula Jones sexual harassment suit, during which he committed perjury regarding his affair with then White House Intern Monica Lewinsky. Schippers was a lifelong Democrat but accepted and took the job in April 1998.
On December 10, 1998, in the House Judiciary Committee, Schippers said these remarkable words: "The President, then, has lied under oath in a civil deposition, lied under oath in a criminal grand jury. He lied to the people, he lied to his Cabinet, he lied to his top aides, and now he's lied under oath to the Congress of the United States. There's no one left to lie to." 
After an investigation that made headlines and television coverage around the world, the committee in December 1998 voted to impeach Clinton, a decision supported by Schippers.
In early 1999, being appalled at how the U.S. Senate conducted the impeachment trial, he penned the book "Sellout: The Inside Story of President Clinton's Impeachment," which vigorously attacked the Clinton White House and portrayed some members of the Senate in an unfavorably. He also proceeded to do some investigative work for the conservative legal watch-dog group Judicial Watch.
- Sellout: The Inside Story of President Clinton's Impeachment by David P. Schippers with Alan P. Henry, Regnery Publishing, 2001 (ISBN 0895261952)