When people think of the beneficiaries of the 1998 Sonny Bono Copyright Term Extension Act, they probably think of Disney. Thanks to Larry Lessig's "Free the Mouse" PR campaign around Eldred v. Ashcroft, Disney's copyright in Steamboat Willy is often thought of as the copyright that Congress wanted to keep from falling into the public domain.
Well, according to this CNN.com story, the shoe is on the other foot when it comes to Peter Pan. A Disney arm published a Peter Pan prequel by Dave Barry and Ridley Pearson in the belief that Peter Pan has entered the public domain in the U.S. Given that the play was first performed in 1904 and book was first published in 1911 (as Peter and Wendy), Disney's belief seems to be pretty reasonable. (1923 is the earliest plausible cut-off year.)
But no. The British hospital to whom J.M. Barrie gave the royalties from his copyrights has started consulting lawyers to sue Disney for copyright infringement, apparently in the belief that their U.S. copyright runs through 2023. I'm trying to figure out what plausible interpretation of U.S. copyright law and/or sad misunderstanding of U.S copyright law would lead to that computation, and not having much luck.
Adding 95 years to 1929, the year in which Barrie made his donation, would add up -- but the 95-year figure applies only to publication dates, and only to publication dates after 1923. They also use a life-plus-70 calculation to conclude that Barrie's 1937 death provides an E.U. copyright good through 2007 -- but you can only get life-plus-70 under U.S. law for unpublished works or ones published after 1978. A 1904 play and a 1911 novel aren't going to fit into any of these categories.
Lessig loves to praise Walt Disney's innovative use of existing cultural materials in creating modern masterpieces. Peter and the Starcatchers fits squarely in that tradition; if anyone would knows which eras can be borrowed from and which are locked away under copyright, it would be Disney.