What is a viral licence?

February 8, 2013

Earlier today, Richard Van Noorden pointed out on Twitter that in this video, at about 5:40, the speaker says that “CC BY is essentially a viral licence”. I was surprised to say the least that the speaker — Sue Joshua, Director of Legal Affairs at John Wiley & Sons — would make such a basic mistake. I’d have expected a copyright lawyer to know what the term “viral licence” means.

Hence this post.

A viral licence is one that imposes the same terms on derived works. If you don’t believe me, here’s the Wikipedia entry, and if you don’t believe that here’s Princeton University’s definition.

This is the meaning of the term “viral licence”. It doesn’t mean “a licence that has suddenly become popular, i.e. ‘gone viral'”. It refers specifically to a licence that (by design) infects numerous works by transmitting itself to from one work to others.

The classic example of a viral licence is the GNU General Public Licence, which is used for much of the world’s most important free software including the Linux kernel. [Disclosure: in my day-job, some of the software we release is under the GPL: YAZ Proxy, Metaproxy, pazpar2, Zebra, IRSpy, MKDru.]

The other best-known viral licence is Creative Commons Attribute-ShareAlike (CC BY-SA). Specifically, this is differentiated from the more common non-viral CC BY licence by the addition of the ShareAlike clause, which says:

Share Alike — If you alter, transform, or build upon this work, you may distribute the resulting work only under the same or similar license to this one.

The reason that CC BY is the most widely used licence for open-access publications is precisely that it is not viral — its non-viral nature means that work licenced using it can be deployed in the widest possible range of circumstances, which is generally what funders want in exchange for their money.

Why am I making such a big deal about this? Because we need to communicate! The term “viral licence” has one meaning, which makes it very easy and unambiguous to talk about. But if we allow Sue Joshua’s confusion to spread, the term will soon become debased just as “open access” has. I was surprised to see in today’s Twitter stream that a couple of people who I expected to know this term seemed unclear on it, so it’s worth clearing up.

[In this post I am not interested in arguing about whether viral licences are a good or a bad thing; just in establishing what they are.]

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2 Responses to “What is a viral licence?”

  1. Michael Richmond Says:

    Can you help me to understand the CC-BY clause, please? Here’s a situation:

    Mike T. creates an awesome piece of software to compute the force exerted by sauropod limbs. He releases it under CC-BY.

    Darren N. uses this piece of software as one little module in a larger piece of software which allows the user to simulate dinosaur locomotion. He releases a package which gives proper credit to Mike T. His package is released under CC-BY also.

    (so far, so good, right?)

    John P. grabs Darren’s software, and uses it to build a game which pits sauropods vs. therapods. John gives credit to Darren.

    Does John have to give credit to Mike T.? If so, then the license seems to be inherited and so “viral”. If not, then does CC-BY only apply to one layer of inheritance?

    Or perhaps I still don’t understand things properly. Please educate me …

  2. ech Says:

    Michael Richmond—John P. doesn’t have to release the derivative work as CC-BY. He can go ahead and sell it/etc and prohibit anyone else from copying *his* portion.


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