While writing my historical fiction, I've included mostly well-known facts that can be found in a variety of published sources. However, one bit of research I'd like to include is one particular (living) historian's theory of a historical event. There's no shortage of theories on this subject out there, but his theory (1) seems to be one of the most likely and well-supported theories, and (2) fits with my story almost perfectly (I've done quite a bit of research myself). He also happens to be a renowned authority on the subject, who's published books on this topic and presented this theory in several documentaries (featured by the Smithsonian, National Geographic, etc). But no matter where I learn about this theory, he's clearly the one who came up with it. Obviously, if this was a work of fiction, I couldn't use it without his permission. (I wouldn't be interested, anyways.) But, since he's promoting this as a legitimate theory, does that change things? I admittedly know very little about copyright law, but from my research it seems that facts can't be copyrighted. (Source: http://bit.ly/1Pe1Mrx) But, when does a theory become a fact? As this event happened over a thousand years ago, we probably won't ever be able to definitively prove his theory right or wrong. So, is this fair game to use? Or, do I need to try to get his permission? (I'm afraid he'll laugh if I ask, as not only am I an unknown writer, but I'd be using his theory in a work of fiction similar to The Da Vinci Code.)
For a proper answer, you'd need to consult a proper lawyer as a proper client. I don't think that it's at all obvious that you couldn't use this theory even if it were fiction. But since it's not, I suppose that doesn't matter. My guess is that it's not copyrightable. The general idea is that you can't copyright facts OR ideas; the thing you can copyright is the expression of ideas. But, proper lawyer. (Grabbing ideas can and does run you into plagiarism, but this doesn't sound like a situation where that would apply.)
This is what Dan Brown did to get sued by the authors of Holy Blood, Holy Grail. Brown won as the court in the UK said there was no infringement.
Thanks for the responses! I was hoping the answer wouldn't be too complex. I think for now I'll proceed with caution, and consult a lawyer before I fully commit to this path. While I was vaguely aware of the controversy surrounding The DaVinci Code, I didn't realize just how much he had copied -- thanks for bringing that up! However, the comparison may be a bit inaccurate... My story stands on its own with or without this theory. It would be a fun bit to include given its plausibility and connection to real facts, but really any theory will do -- it just needs to be wrapped up in a bit of mystery for the characters to solve, to get them from point A to point B. Unlike The DaVinci code vs Holy Blood, Holy Grail, in my story the central premise, conflict, setting, etc are all original.
