Kahle v. AshcroftEdgar Rice Burroughs' The Martian Tales Series
originally submitted by Eli:
Edgar Rice Burroughs' wrote 11 books in The Martian Tales Series starting in 1911 with "A Princess of Mars" and ending somewhere after 1930 with "John Carter of Mars". Half of the series has already fallen into the public domain but because of the Sonny Bono Term Extension Act the second half of the series has not (but would have) fallen into the public domain.
Public Domain:
A Princess of Mars
The Gods of Mars
The Warlord of Mars
Thuvia, Maid of Mars
The Chessmen of Mars
Still Copyrighted:
The Master Mind of Mars
A Fighting Man of Mars
Swords of Mars
Synthetic Men of Mars
Llana of Gathol
John Carter of Mars
Stifled uses
Eli:
It is ambiguous to know if using material from The Martian Tales Series (even if only from the public domain works) would infringe the copyright of the works from the second half of the series. The Sonny Bono Term Extension stifled the ability to freely use the entire Martian Tales Series as half of it was cut short from entering the public domain.
As a hobbyist game developer I was interested in using material from The Martian Tales Series for a video game deriving from the rich world created in The Martian Tales Series. Unfortinately I am unable to pursue creating a work derived from the first half of the series for fear of infringing the copyright of the second half of the series.