Choose a License

Overview

Teaching: 5 min
Exercises: 0 min

Questions

• What licensing information should I include with my work?

Objectives

• Explain why adding licensing information to a repository is important.

• Choose a proper license.

• Explain differences in licensing and social expectations.

• Creative works are automatically eligible for intellectual property (and thus copyright) protection
• Reusing creative works without a license is dangerous
  • Because copyright holders could sue you for copyright infringement
• Every repository (version control or otherwise) should therefore include an explicit license
  • Usually LICENSE or LICENSE.txt in root directory
• Clearly states under which license(s) the content is being made available
  • Plural because code, data, and text may be covered by different licenses
• Important to decide early
  • Otherwise, each time a new collaborator starts contributing, they will hold copyright on their work and will thus need to be asked for approval when a license is chosen
• A few licenses are by far the most popular
  • Choosing a common license makes project more intelligible
  • Don’t write your own (even if you are a lawyer)
• Common licenses
  • Open Source Inititative license list
  • Free Software Foundation license list
  • choosealicense.com will help you find a license that suits your needs
• For code:
  • MIT/BSD: do whatever you want as long as you cite the original source, and we accept no responsibility if things go wrong
  • GPL: as above, but changes must be distributed
• For data and text:
  • CC-0: public domain (for data)
  • CC-BY: do whatever you want as long as you cite the original source (for papers)
  • Other restrictions all inhibit legitimate use cases
    • -ND: no derivative works
    • -NC: no commercial use (without explicit permission)
    • -SA: share-alike
• Considerations:
  • Do you want to license the code at all?
  • Is the content you are licensing source code?
  • Do you require people distributing derivative works to also distribute their code?
  • Do you want to address patent rights?
  • Is your license compatible with the licenses of the software you depend on?
    • E.g., can’t use MIT on top of GPL
• See this paper and this blog post for overviews from a scientist’s point of view

Can I Use an Open License?

Find out whether you are allowed to apply an open license to your software. Can you do this unilaterally, or do you need permission from someone in your institution? If so, who?

What Licenses Do My Dependencies Use?

Make a list of the licenses used by the projects that your project depends on. Are there any conflicts between them and the license that you have chosen?

Key Points

• People who incorporate GPL’d software into their own software must make their software also open under the GPL license; most other open licenses do not require this.

• The Creative Commons family of licenses allow people to mix and match requirements and restrictions on attribution, creation of derivative works, further sharing, and commercialization.

• People who are not lawyers should not try to write licenses from scratch.