Fact sheet P-20: Copyleft
Issued: 10th May 2007
- What is Copyleft?
Copyleft is a term that describes a copyright licencing scheme where the author surrenders some of his rights. Typically a copyleft licence will allow a work to be freely copied, distributed or adapted, provided that all copies or modified versions are also freely available under the same licence.
The actual word ‘copyleft’ has no legal meaning in itself, it is simply a play on the word ‘copyright’.
Copyleft is not the opposite of copyright, merely a way of describing a more ‘liberal’ copyright licencing policy. The most well known example is the GNU General Public License (GPL).
- Copyleft licensing
Any form of copyright work can be subject to a licensing arrangement, and the licence is nothing more than a way of changing the restrictions placed on the work. By default, copyright law prohibits acts of copying, distribution or adaptation without the author’s consent.
A licensing scheme such as GPL gives everyone permission to adapt or distribute copies of the work freely, provided that any copies or adaptations are subject to the same licence as the original.
- Creating a licence.
The basic areas that a licence would cover are:
- Release of rights: Which normally prohibited actions may be allowed and what conditions should apply?
- Commercial use: Can a licensee use the work within a commercial setting? i.e. for direct or indirect monetary gain, or to add content to a commercial project.
- Derivative works: Can the licensee adapt or build upon the work? Or must it be presented as the author created it.
- Distribution and copying: When and how may a work be copied or distributed. In the case of copyleft works, the copyright owner will typically permit others to distribute copies of the work only if they include the original licence, this is often referred to as a ‘share alike’ licence.
- Jurisdiction: Should the license be subject to the law of a specific country or region.
- Licensing your own work
Fortunately, you do not need to be a legal professional to draw up the licence, there are a number of freely available licences that can be applied to your work.
The GNU project provides a number of licences that can be applied to your own works, including the GNU General Public License (GPL) and Lesser General Public License (LGPL) for software licensing and the GNU Free Documentation License (FDL) for documents.
Creative Commons also provide a free licence generator for all types of work and uses.
- Copyleft vs public domain
The typical purpose of a copyleft licence is to ensure that the work and its derivatives will always be freely available. If the author simply relinquished his copyright (i.e. puts the work in the public domain), then it would be possible for someone else to commercially market the work for their own gain; if no copyright exists, there is no way to prevent this.
A licence such as GPL ensure that this does not happen. As the work is still subject to copyright, the author still has some control.
- Participative projects
In some areas, particularly software design, a number of contributors may work collaboratively on a common project, some most notable examples being Open Office and Linux. A copyleft licence makes it easier for individuals to contribute to a project and ensures that the whole community benefits from their work.
- Further reading
The GNU project page ‘What is copyleft?’.
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This fact sheet is intended only as an introduction to ideas and concepts only. It should not be treated as a definitive guide, nor should it be considered to cover every area of concern, or be regarded as legal advice.