When Rep. Joe Wilson, R-S.C., shouted "You lie!" during one of President Obama's early addresses to Congress, the outburst was unprecedented. Yet, in the charged political climate of the past two years, hot partisan rhetoric has continued, and accusations of lying have been rife. Historians say that false charges by competing candidates and lies by government officials to hide their actions from the public are a staple of politics going back to the 1800 presidential campaign between Thomas Jefferson and John Adams. Some legal scholars point out that the First Amendment broadly protects political speech, even when it's false. Some blame a lazy media -- and clearly partisan media outlets like Fox News and MSNBC -- for allowing more misinformation to flourish today. And some point out that political speech can be misleading without being flat-out lying.

Marcia Clemmitt is a veteran social-policy reporter who joined CQ Researcher after serving as editor in chief of Medicine and Health, a Washington-based industry newsletter, and staff writer for The Scientist. She has also been a high school math and physics teacher. She holds a bachelor's degree in arts and sciences from St. Johns College, Annapolis, and a masters degree in English from Georgetown University.