For most of history, a great character or story or song has passed from its original creator into the public domain. Shakespeare and Charles Dickens and Beethoven are long dead, but Macbeth and Oliver Twist and the Fifth Symphony are part of our shared cultural heritage, free to be used or reinvented by anyone on the planet who is so inclined.
But 15 years ago, U.S. President Bill Clinton signed the Sonny Bono Copyright Term Extension Act, which retroactively extended copyright protection. As a result, the great creative output of the 20th century, from Superman to "Gone With the Wind" to Gershwin's "Rhapsody in Blue," were locked down for an extra 20 years.
It was a windfall for the families and corporations that owned these lucrative copyrights. But it meant these iconic works would be off-limits to those who wanted to reuse or reinvent them without permission. And hundreds of thousands of lesser-known works are not available at all, because there is no cost-effective way to obtain permission to republish them.