Early in the process of depositing data to the Dryad repository,  authors are asked to consent to the explicit release of their data into the public domain under the terms of a Creative Commons Zero (CC0) waiver. We are frequently asked why Dryad uses CC0 rather than a license such as CC-BY, and it is important for all users to understand the rationale for this, as well as its implications.

Obviously, one of the primary purposes of archiving data in Dryad is to enable its reuse by others.  Having clear and open terms of reuse helps realize that goal.  (Along with having well-organized data, good documentation, persistent file-formats, etc.)

CC0 was crafted specifically to reduce any legal and technical impediments, be they intentional and unintentional, to the reuse of data.   In most cases, CC0 does not actually affect the legal status of the data, since facts in and of themselves are not eligible for copyright in most countries (e.g. see this commentary from Bitlaw regarding U.S. copyright law).  But where they are, CC0 waives copyright and related rights to the extent permitted by law.

Importantly, CC0 does not exempt those who reuse the data from following community norms for scholarly communication.  It does not exempt researchers from reusing the data in a way that is mindful of its limitations.  Nor does it exempt researchers from the obligation of citing the original data authors.  However, like other scientific norms, these expectations are best articulated and enforced by the community itself through processes such as peer review.

In fact, by removing un-enforcable legal barriers, CC0 facilitates the discovery, re-use, and citation of that data.

“Community norms can be a much more effective way of encouraging positive behaviour, such as citation, than applying licenses. A well functioning community supports its members in their application of norms, whereas licences can only be enforced through court action and thus invite people to ignore them when they are confident that this is unlikely.” (Panton Principles FAQ)

Dryad’s policy ultimately follows the recommendations of Science Commons, which discourage researchers from presuming copyright and using licenses that include “attribution” and “share-alike” conditions for scientific data.

Both of these conditions can put legitimate users in awkward positions.  First, specifying how “attribution” must be carried out may put a user at odds with accepted citation practice:

“when you federate a query from 50,000 databases (not now, perhaps, but definitely within the 70-year duration of copyright!) will you be liable to a lawsuit if you don’t formally attribute all 50,000 owners?” Science Commons Database Protocol FAQ)

While “share-alike” conditions create their own unnecessary legal tangle:

“ ‘share-alike’ licenses typically impose the condition that some or all derivative products be identically licensed. Such conditions have been known to create significant “license compatibility” problems under existing license schemes that employ them. In the context of data, license compatibility problems will likely create significant barriers for data integration and reuse for both providers and users of data.” (Science Commons Database Protocol FAQ)

Thus,

“… given the potential for significantly negative unintended consequences of using copyright, the size of the public domain, and the power of norms inside science, we believe that copyright licenses and contractual restrictions are simply the wrong tool [for data], even if those licenses and contracts are used with the best of intentions.” (Science Commons Database Protocol FAQ)

Furthermore, Dryad’s use of CC0 to make the terms of reuse explicit has some important advantages:

• interoperability: Since CC0 is both human and machine-readable, other people and indexing services will automatically be able to determine the terms of use.
• universality: CC0 is a single mechanism that is both global and universal, covering all data and all countries.  It is also widely recognized.
• simplicity: there is no need for humans to make, and respond to, individual data requests, and no need for click-through agreements.  This allows more scientists to spend their time doing science.

It is important to note that if you have data that, due to pre-existing agreements, cannot be released under the terms of CC0, please do not deposit that data to Dryad.  Journals that require data archiving in Dryad as a condition of publication can make exceptions for such special cases.

Footnote:  Dryad had originally applied CC-BY to all its contents.  Dryad’s Board made the decision to use CC0 in May 2009.