Apparently Games Workshop owns the trademarked term “Space Marines”, so nobody else is supposed to use it:
For years, there have been stories about Games Workshop being trademark bullies and sending threats to people who use the term “space marine” in connection with games. But now that they’ve started publishing ebooks, Games Workshop has begun to assert a trademark on the generic, widely used, very old term “space marine” in connection with science fiction literature.
[. . .]
A few important notes:
* Amazon didn’t have to honor the takedown notice. Takedown notices are a copyright thing, a creature of the Digital Millennium Copyright Act. They don’t apply to trademark claims. This is Amazon taking voluntary steps that are in no way required in law.
* Games Workshop’s strategy is to make “space marine” less generic by launching high profile, bullying attacks on everyone who uses it, so that there will come a day when people hearing the phrase immediately conclude that it must be related to Games Workshop, because everyone know what colossal dicks they are whenever anyone else uses the phrase
* Trademarks only apply to commercial works. You can and should use “space marine” in your everyday speech, fanfic, tweets and so on. For one thing, it will undermine Games Workshop’s attempts to homestead our common language.
Update: John Scalzi clearly feels the claim lacks merit:
I am not a lawyer, so factor that in here. That said: Games Workshop, really? You know, a simple search on the term “space marines” over at Google Books shows a crapload of prior art for “space marines” in science fiction literature, from the 1936 Amazing Tales novelette “The Space Marines and the Slavers” by Bob Olsen, to Robert Heinlein’s novel Space Cadet, to the very recent use of the term in The Sheriff of Yrnameer by Michael Reubens and So You Created a Wormhole: The Time Traveler’s Guide to Time Travel by Phil Hornshaw and Nick Hurwitch. There is no lack of evidence that the phrase “space marines” has been used rather promiscuously in science fiction literature up to this point.
To argue, as Games Workshop must, that the phrase “space marines” has a distinctive character in science fiction literature relating only to their product involves, shall we say, a certain studied ignorance of the field. Table top games? Possibly; I’m not an expert. Science fiction literature? You have got to be kidding. It’s pretty damn generic in this field, and was long before 1987, when Warhammer 40,000 was created in game form . Nor does it seem, as far as I know, that Games Workshop attempted to claim trademark on the phrase “space marine” before, despite a veritable plethora of Warhammer 40K tie-in literature using the phrase.