Creative Commons Attribution-ShareAlike License

Creative Commons Attribution-ShareAlike License
Name	Creative Commons Attribution-ShareAlike License
Abbreviation	CC BY-SA
Version	4.0 International
Author	Creative Commons
Publisher	Creative Commons
Published	2002 (v1.0)
Website	https://creativecommons.org/licenses/by-sa/4.0/

Creative Commons Attribution-ShareAlike License. It is a prominent copyleft license published by the non-profit organization Creative Commons. The license allows for the free sharing and adaptation of creative works, provided that the original creator is credited and any new works are distributed under identical terms. This "share-alike" mechanism is designed to foster a growing commons of freely reusable content, influencing projects from Wikipedia to major open-source software initiatives.

Overview

The license is one of several public copyright licenses developed by Lawrence Lessig and his colleagues at Creative Commons. It is specifically designed to permit broad freedoms while ensuring downstream reciprocity, a principle central to the free software movement pioneered by Richard Stallman and the Free Software Foundation. Unlike more permissive alternatives like the MIT License, it requires derivative works to be licensed under the same terms, creating a viral or hereditary effect on subsequent creations. This model has been instrumental in the growth of collaborative projects, most notably the Wikimedia Foundation's array of projects, which rely on it as a core content license.

Terms

The core obligations for users are attribution and share-alike. The attribution clause mandates that users must give appropriate credit to the original author, provide a link to the license, and indicate if changes were made, similar to requirements found in the Apache License 2.0. The share-alike clause stipulates that if you remix, transform, or build upon the material, you must distribute your contributions under this same license. These terms apply worldwide for the duration of the work's copyright and are irrevocable. Key legal concepts embedded in the terms include waivers of moral rights where possible and clarity on sublicensing rights, drawing from established practices in copyright law in the United States and the European Union.

Version history

The license has evolved through several iterations. Version 1.0 was launched in 2002, following the establishment of Creative Commons. Version 2.0 introduced important clarifications regarding trademark rights. The widely adopted version 3.0, released in 2007, improved international enforceability by aligning with the Berne Convention and addressing issues like database rights relevant in jurisdictions like the European Union. The current version 4.0, published in 2013, represents a major global unification, improving readability for non-lawyers and explicitly covering sui generis database rights and the right of publicity. Each version is backward compatible, allowing content under older versions to be relicensed under newer ones.

Compatibility

A significant legal discussion surrounds its compatibility with other copyleft licenses. It is one-way compatible with the GNU Free Documentation License (GFDL), allowing content under that license to be incorporated. However, it is not inherently compatible with the strong copyleft GNU General Public License (GPL) used for software, though projects like WordPress have successfully combined code and content under different licenses. Creative Commons maintains a formal compatibility mechanism, primarily with other Creative Commons licenses, and declares it compatible with the Free Art License. Debates over compatibility often involve the Free Software Foundation and the Open Source Initiative.

Use and adoption

Adoption is extensive across digital and cultural projects. It is the primary content license for Wikipedia and all other Wikimedia projects, making it one of the most widely used licenses in the world. Major institutions like the Metropolitan Museum of Art and the British Library have released digital collections under this license. It is also used for documentation for projects like Ubuntu and for open educational resources by organizations like Khan Academy. The license's use in government data initiatives, such as those by the European Commission, and for academic research, including projects funded by the National Science Foundation, further demonstrates its reach.

Legal and philosophical basis

Legally, it operates as a conditional grant of rights under existing copyright statutes, such as the Copyright Act of 1976 in the United States. Philosophically, it is rooted in the copyleft ethos of the free software movement and the broader commons-based peer production model theorized by scholars like Yochai Benkler. It represents a pragmatic application of open content principles, seeking a middle ground between the public domain and full copyright restriction. The license has been tested in courts in several countries, including Germany and Spain, helping to solidify its legal standing and its role in movements for open access and open knowledge.

Category:Creative Commons licenses Category:Copyleft licenses Category:Open content licenses