Wow, I think this new decision cleans up a number of loose ends left by the district judge. It's not especially clear in the Guardian article, but this is the Circuit Court (one layer below the Supreme Court) decision of the appeal by the Conan Doyle Estate of a District Court decision made at the end of last year.
The District Court decision by Ruben Castillo (http://freesherlock.files.wordpress.com/2013/12/klinger-orde...) went largely in favor of Klinger, saying that the pre-1923 stories were public domain. But it left a lot of uncertainty about how incidental details ("increments of expression") from the later stories were to be treated. There's a good summary of the District decision here: http://tushnet.blogspot.com/2014/01/guest-post-betsy-rosenbl...
In addition to affirming the earlier District decision (Klinger can publish without fear of being sued), this brand new Circuit decision by Richard Posner seems like it clears up a lot of the uncertainty and offers much clearer guidelines for future decisions. And it does it decisively and with considerable flair: http://freesherlock.files.wordpress.com/2013/02/klinger-7th-...
We cannot find any basis in statute or case law for ex-
tending a copyright beyond its expiration. When a story
falls into the public domain, story elements—including
characters covered by the expired copyright—become fair
game for follow-on authors...
The decision itself is worth reading, definitely clearer and more engaging than most of the newspaper coverage.