Attorneys representing California artist Shepard Fairey in his legal dispute with the Associated Press (AP) over copyright ownership of a Barack Obama presidential campaign poster image are now citing a legal defense called, the doctrine of unclean hands‚ to help negate claims of copyright infringement.

The doctrine states that parties cannot seek damages for an activity in which they partake themselves. Referencing this doctrine, Fairey's team maintains that the AP regularly uses images in stories without permission from the artist...