**The following post was written by Simon Chignard, author of *[L’Open data: Comprendre l’ouverture des données publiques](http://www.amazon.fr/LOpen-data-Comprendre-louverture-publiques/dp/2916571701)*. The post was originally posted on [Simon’s blog](http://donneesouvertes.info) following the [launch of the Open Knowlege Foundation French national group](http://blog.okfn.org/2012/12/21/what-happened-at-the-1st-open-knowledge-foundation-france-meet-up/), and has been translated by Samuel Goëta from OKFN France.**
##Open data and the commons: an old story?
There is a direct link between the open data movement and the philosophy of common goods. Open data are an illustration of the notion of common informational goods proposed by [Elinor Ostrom](http://en.wikipedia.org/wiki/Elinor_Ostrom), winner of the 2009 Nobel Prize for economics. Open data belong to everyone and, unlike water and air (and other common goods), they are non-exclusive: **their use by one does not prevent others**. If I reuse an open data set, this does not prevent other reusers from doing so. This proximity between the commons and open data is also suggested by the presence of the initiator of Creative Commons licences, Lawrence Lessig, at the [2007 Sebastopol](http://donneesouvertes.info/2012/04/30/comment-lopen-data-est-devenu-un-objet-politique/) meeting in which the concept of open data itself was defined.
But despite the strong conceptual and historical linkages, it seems that we, as actors of open data, are often shy to reaffirm the relationship. In our efforts to encourage public and private bodies to embrace open data, we seem almost embarrassed of this cornerstone philosophy. The four proposals I make here aim at one thing: not letting it drop!
###Idea #1: defend a real choice in terms of open data licences (“pro-choice” approach)
On paper, that sounds clear: there is a real choice in France in terms of open data licences. On one side, the [open licence](http://www.etalab.gouv.fr/pages/Licence_ouverte_Open_licence-5899923.html) offered by Etalab (the French government institution in charge of government open data), on the other side, the Open Database License ([ODbL](http://opendatacommons.org/licenses/odbl/)). Government services must use the former, some local authorities have chosen the latter, generally based on some conception of the relationship between the commons and open data.
In practice, this choice is hindered by the difficulties, real or perceived, of the ODbL licence. The two licences are distinguished by the ODbL’s obligation to share alike, which is clearly a product of a belief in the common pot (if I use it, I must recontribute). But a strange music is playing in France, which warns against this “contaminating” licence. ODbL is accused of being against business, coming “from abroad”, or being the source of unpredictable dangers (such as [counterfeiting](http://www.usinenouvelle.com/article/droits-et-devoirs-de-l-open-data.N186232)).
We find ourselves in a situation where, at the same moment as big projects such as Open Street Map are adopting ODbL, new entrants in open data apply – sometimes in good faith – the principle of the least effort: “that share-alike thing seems complicated, we don’t really know the potential risks, I’d rather choose Licence Ouverte”.
As the initiator of the ODbL licence, the Open Knowledge Foundation should be its first promoter, explain its mechanisms and opportunities (not only to [block Google](http://donneesouvertes.info/2012/11/15/monetiser-les-donnees-du-transport-public-chiche/)). So that a real choice of open data licences stays possible (pro-choice approach)!
But the ODbL licence cannot by itself defend open data as part of the digital commons – below are three further tactics which need to be employed alongside it.
###Ideal #2: the General Interest Data, G.I.D.
Let’s take an example that matters to everyone, which was addressed during a recent workshop run by Net:Lab – access to housing. In France, who has the best knowledge of the housing market? Who knows rent prices in great details and in real time, with an address and a complete description of the accommodation? Not the council, nor tax services, nor even the housing minister – but [a private actor in real estate ads](http://www.groupe-seloger.com/ ).
In France, we have a law for personal data ([CNIL](http://fr.wikipedia.org/wiki/Commission_nationale_de_l%27informatique_et_des_libert%C3%A9s#Loi_de_1978_et_modification_en_2004w) law), another for public data ([CADA](http://www.legifrance.gouv.fr/affichTexte.do?cidTexte=LEGITEXT000006068643&dateTexte=20080614) law). But what about data – personal, public or private – which serves the general interest? With a clearer and more dynamic vision of rents, one can imagine that everyone would be more informed on the real prices of the market (while making sure to limit the side effects of transparency).
Without demanding the requisition of the data (and of empty flats), one can imagine a digital tax system encouraging its release. There is already a tax break in France for research, why not for open data?
As mentioned previously, this would require the definition of a new class of data, the G.I.D. (General Interest Data), associated with specific rights of access and reuse.
(Obviously, G.I.D. raises as many questions as it tackles – for example *who will define general interest*?)
###Idea #3: Contribution peering: I contribute/I receive
The first period of open data has seen public actors (local authorities or governments) release their data to users, mainly developers. The emerging open data movement is becoming infinitely richer and more complex. Although the division of roles between producers and re-users seems quite established, it is evolving: public and collaborative open data are starting to [mutually enrich](http://data.paysdelaloire.fr/donnees/?facet%5Bcategories%3AMobilit%C3%A9%5D=on&keywords=&sort_search=date) each other, companies are starting to deliver data on themselves back to clients. How can we design a contribution mechanism which takes into account these evolutions, so as to make “common pots”?
The first step I would suggest is “peering of contribution” – as already exists for boat positioning systems (AIS data). Collaborative website [Marine Traffic](http://www.marinetraffic.com/ais/), launched in 2007, is now the first website in the world for tracking global naval traffic. More than 1000 contributors (equipped with an AIS receiver connected to the Internet) allow the daily tracking of 65,000 ships. The website now displays more that 2 million page views – per day (source: interview S. Chignard with Dimitris Lekkas, Greek scholar who developed the project). Everyone can visualise the data on the map displayed on the website, but if you wish to access raw data, you need to contribute to the service by connecting a new AIS receiver. Hence [contribution peering](http://www.marinetraffic.com/ais/fr/exporttext.aspx) encourages everyone to enhance the service (Marine Traffic is not the only website doing this – see for example the [AIS Hub](http://www.aishub.net/ais-tracking-join-us.html))
###Idea #4: Contributive pricing on use (GET>POST)
The last suggestion I would like to make for the development and defence of an open data commons, is be pricing on use – an idea already mentioned in [my blog about transport data](http://donneesouvertes.info/2012/11/15/monetiser-les-donnees-du-transport-public-chiche/). This would involve a variable pricing scheme for the use of data. APIs allow particularly well for this pricing method.
Let’s imagine, for example, that access to our G.I.D. be free for all, but that a contribution may be asked to the biggest users of an API who behave nearly as free riders (in economic theory, those who make use of others’ contributions without ever contributing themselves). Hence it would be free to anyone to choose whether to contribute by enhancing the data (updating, correcting), or by paying out-of-pocket!