20 years ago today: Bill Clinton became the first sitting president to testify as the subject of a grand jury investigation. The president’s testimony was related to his affair with an intern, Monica Lewinsky, which Clinton initially denied /1 
The testimony capped a four-year investigation into President Clinton and First Lady Hillary Clinton’s alleged involvement in a series of alleged scandals. As the investigation unfolded, an independent prosecutor, Kenneth Starr, learned of the Lewinsky affair /2
When questioned, Clinton denied the affair, which led Starr to charge him with perjury and obstruction of justice. The president was impeached by the House, but acquitted by the Senate. Only one other president has ever been impeached: Andrew Johnson—who also survived his trial
