You may have noticed that CC-BY license over there on the right-hand sidebar. That’s the basic Attribution license from Creative Commons. So why not non-commercial (NC), share-alike (SA), or no derivatives (ND)? And why use a CC license at all?
Two caveats: I am not a lawyer, and the dust has not settled on some of these issues. Creative Commons is currently finalizing version 4.0 of their licenses, and the documentation should be out in the next few months.
The purpose of CC licenses is to reduce the friction in the exchange of information. Without a CC license, if others want to use your work, they must weigh the four fair use factors (often quite fuzzy and subjective), or they must ask permission. The first is a judgement call (which might result in a lawsuit) and the second doesn’t scale very well. In academia, the emphasis should be on sharing and building knowledge, not on permissions and lawyers. Friction is removed from the system when authors give permissions in advance by using a CC license.
I’ve personally cycled through using a variety of CC licenses, based on a somewhat face-value interpretation of them. Unfortunately things can get complicated, and the meaning of terms is not always what you think. The best example is “noncommercial.” I interpreted this to mean that for-profit entities could not use my work, but non-profits like universities could. Not necessarily, according to CC’s FAQ:
“Please note that CC’s definition does not turn on the type of user: if you are a non profit or charitable organization, your use of an NC-licensed work could run afoul of the NC restriction; and if you are a for-profit entity, your use of an NC-licensed work does not necessarily mean you have violated the term.”
I became concerned when opinions were issued that would even block use in teaching under a NC license (see a translated report from German Wikimedia/CC, summarized in this blog post, and see an excellent blog post by Peter Murray-Rust).
So what about share-alike (SA)? This is the “copyleft” condition that stands copyright on its head by requiring all subsequent use to invoke the same license, and best known for its use in Wikipedia . The problem is that this “viral” license is a restriction that prevents use by those not able to license the same way.
I use CC-BY for this blog and my archived work for the reasons mentioned by Peter Murray-Rust: it’s the simplest license, avoids restrictions, avoids “infecting” other licenses when aggregated with other works, enables text-mining and other automated uses, and is the license used by major OA journal publishers like PLOS and PeerJ.
I encourage you to use CC-BY whenever possible for your work, but read the licenses carefully and choose your own.
Open licensing to enable greater downstream use has been a part of the open access movement from the beginning, and it’s starting to get a lot more attention (e.g., How Open Is It?). Open access is more than just making material available on the Internet.