The Los Angeles artist behind an iconic poster that became a symbol of President Barack Obama's campaign four years ago pleaded guilty to a criminal misdemeanor Friday stemming from his actions during a copyright dispute over the poster.

At a hearing in Manhattan federal court Friday, Shepard Fairey, 42 years old, admitted that he fabricated documents and lied during the discovery process in copyright litigation with the Associated Press. As a result, he violated a judge's order.

The...