From the abstract:
Copyfraud is everywhere. False copyright notices appear on modern reprints of Shakespeare's plays, Beethoven's piano scores, greeting card versions of Monet's Water Lilies, and even the U.S. Constitution. Archives claim blanket copyright in everything in their collections. Vendors of microfilmed versions of historical newspapers assert copyright ownership. These false copyright claims, which are often accompanied by threatened litigation for reproducing a work without the owner's permission, result in users seeking licenses and paying fees to reproduce works that are free for everyone to use.Link
Copyright law itself creates strong incentives for copyfraud. The Copyright Act provides for no civil penalty for falsely claiming ownership of public domain materials. There is also no remedy under the Act for individuals who wrongly refrain from legal copying or who make payment for permission to copy something they are in fact entitled to use for free. While falsely claiming copyright is technically a criminal offense under the Act, prosecutions are extremely rare. These circumstances have produced fraud on an untold scale, with millions of works in the public domain deemed copyrighted, and countless dollars paid out every year in licensing fees to make copies that could be made for free. Copyfraud stifles valid forms of reproduction and undermines free speech.