Software Licensing

The Software Freedom Law Center[1] defines the following common approaches to copyright handling in software projects:[2]

  1. per file handling

  2. centralized

SFLC explains that no copyright information does not yield copyright. Thus no copyright header is preferred way to go since it minimizes maintenance work. No yearly updates have to be performed. Future contributors do not have to be added manually, your version control system handles that way better than you anyway.

FSF suggest to use CC0[3][4]

CC tells something about license headers for files.[5]

Atwood suggest to pick any license.[6]

Recommendation

Follow the suggesting of the FSF and pick the Creative Commons Zero license.[4]. Compared to similar licenses like the WTFPL[7] or UNLICENSE[8] which are often critized for lacking legal language, the CC0’s only downside seems to be a missing OSI[9] stamp of approval[10]. The problem here is that the CC0 does not grant any (implicit) trademark or patent rights, thus placing users of your software in a position where they can legally use your software but are forced to pay royalties for using your patent implemented by that software.[11] In order to solve that problem, place all your trademarks and patent rights under the same CC0 license. If that is not possible, use the CC0 in your advantage and simple fork the software and re-release it in whatever license, whatever user requires. Cut down on maintenance by using a multi-license approach.[12]

The CC0 license is probably not DFSG[13] compatible because of the above issue. If you plan on release software into Debian repositories, use the mentioned multi-license approach. A short license like the ISC[14] is DFSG compatible and won’t clutter your LICENSE file.

Apply the following setup to your project in order to use the CC0 license. The setup is intended to reduce ongoing maintenance work with regards to copyright information while still supporting multiple contributors.

1) Use the following header for all source files. Replace $MY_PROJECT with the name of your project.

This file is part of $MY_PROJECT. It is subject to the license terms in the LICENSE file found in the top-level
directory of this distribution and at http://creativecommons.org/publicdomain/zero/1.0/. No part of $MY_PROJECT, including
this file, may be copied, modified, propagated, or distributed except according to the terms contained in the
LICENSE file.
This header does not contain the typical copyright fragments, like the year of publication or the author. The SLFC[2] explains that missing copyright information does not void your copyright at all - thus it can be safely removed. Instead the file header simply redirects the reader to the LICENSE file in the root of the project.

2) Add a file called LICENSE in the root of your project with the following legal code:

Creative Commons Legal Code

CC0 1.0 Universal

    CREATIVE COMMONS CORPORATION IS NOT A LAW FIRM AND DOES NOT PROVIDE
    LEGAL SERVICES. DISTRIBUTION OF THIS DOCUMENT DOES NOT CREATE AN
    ATTORNEY-CLIENT RELATIONSHIP. CREATIVE COMMONS PROVIDES THIS
    INFORMATION ON AN "AS-IS" BASIS. CREATIVE COMMONS MAKES NO WARRANTIES
    REGARDING THE USE OF THIS DOCUMENT OR THE INFORMATION OR WORKS
    PROVIDED HEREUNDER, AND DISCLAIMS LIABILITY FOR DAMAGES RESULTING FROM
    THE USE OF THIS DOCUMENT OR THE INFORMATION OR WORKS PROVIDED
    HEREUNDER.

Statement of Purpose

The laws of most jurisdictions throughout the world automatically confer
exclusive Copyright and Related Rights (defined below) upon the creator
and subsequent owner(s) (each and all, an "owner") of an original work of
authorship and/or a database (each, a "Work").

Certain owners wish to permanently relinquish those rights to a Work for
the purpose of contributing to a commons of creative, cultural and
scientific works ("Commons") that the public can reliably and without fear
of later claims of infringement build upon, modify, incorporate in other
works, reuse and redistribute as freely as possible in any form whatsoever
and for any purposes, including without limitation commercial purposes.
These owners may contribute to the Commons to promote the ideal of a free
culture and the further production of creative, cultural and scientific
works, or to gain reputation or greater distribution for their Work in
part through the use and efforts of others.

For these and/or other purposes and motivations, and without any
expectation of additional consideration or compensation, the person
associating CC0 with a Work (the "Affirmer"), to the extent that he or she
is an owner of Copyright and Related Rights in the Work, voluntarily
elects to apply CC0 to the Work and publicly distribute the Work under its
terms, with knowledge of his or her Copyright and Related Rights in the
Work and the meaning and intended legal effect of CC0 on those rights.

1. Copyright and Related Rights. A Work made available under CC0 may be
protected by copyright and related or neighboring rights ("Copyright and
Related Rights"). Copyright and Related Rights include, but are not
limited to, the following:

  i. the right to reproduce, adapt, distribute, perform, display,
     communicate, and translate a Work;
 ii. moral rights retained by the original author(s) and/or performer(s);
iii. publicity and privacy rights pertaining to a person's image or
     likeness depicted in a Work;
 iv. rights protecting against unfair competition in regards to a Work,
     subject to the limitations in paragraph 4(a), below;
  v. rights protecting the extraction, dissemination, use and reuse of data
     in a Work;
 vi. database rights (such as those arising under Directive 96/9/EC of the
     European Parliament and of the Council of 11 March 1996 on the legal
     protection of databases, and under any national implementation
     thereof, including any amended or successor version of such
     directive); and
vii. other similar, equivalent or corresponding rights throughout the
     world based on applicable law or treaty, and any national
     implementations thereof.

2. Waiver. To the greatest extent permitted by, but not in contravention
of, applicable law, Affirmer hereby overtly, fully, permanently,
irrevocably and unconditionally waives, abandons, and surrenders all of
Affirmer's Copyright and Related Rights and associated claims and causes
of action, whether now known or unknown (including existing as well as
future claims and causes of action), in the Work (i) in all territories
worldwide, (ii) for the maximum duration provided by applicable law or
treaty (including future time extensions), (iii) in any current or future
medium and for any number of copies, and (iv) for any purpose whatsoever,
including without limitation commercial, advertising or promotional
purposes (the "Waiver"). Affirmer makes the Waiver for the benefit of each
member of the public at large and to the detriment of Affirmer's heirs and
successors, fully intending that such Waiver shall not be subject to
revocation, rescission, cancellation, termination, or any other legal or
equitable action to disrupt the quiet enjoyment of the Work by the public
as contemplated by Affirmer's express Statement of Purpose.

3. Public License Fallback. Should any part of the Waiver for any reason
be judged legally invalid or ineffective under applicable law, then the
Waiver shall be preserved to the maximum extent permitted taking into
account Affirmer's express Statement of Purpose. In addition, to the
extent the Waiver is so judged Affirmer hereby grants to each affected
person a royalty-free, non transferable, non sublicensable, non exclusive,
irrevocable and unconditional license to exercise Affirmer's Copyright and
Related Rights in the Work (i) in all territories worldwide, (ii) for the
maximum duration provided by applicable law or treaty (including future
time extensions), (iii) in any current or future medium and for any number
of copies, and (iv) for any purpose whatsoever, including without
limitation commercial, advertising or promotional purposes (the
"License"). The License shall be deemed effective as of the date CC0 was
applied by Affirmer to the Work. Should any part of the License for any
reason be judged legally invalid or ineffective under applicable law, such
partial invalidity or ineffectiveness shall not invalidate the remainder
of the License, and in such case Affirmer hereby affirms that he or she
will not (i) exercise any of his or her remaining Copyright and Related
Rights in the Work or (ii) assert any associated claims and causes of
action with respect to the Work, in either case contrary to Affirmer's
express Statement of Purpose.

4. Limitations and Disclaimers.

 a. No trademark or patent rights held by Affirmer are waived, abandoned,
    surrendered, licensed or otherwise affected by this document.
 b. Affirmer offers the Work as-is and makes no representations or
    warranties of any kind concerning the Work, express, implied,
    statutory or otherwise, including without limitation warranties of
    title, merchantability, fitness for a particular purpose, non
    infringement, or the absence of latent or other defects, accuracy, or
    the present or absence of errors, whether or not discoverable, all to
    the greatest extent permissible under applicable law.
 c. Affirmer disclaims responsibility for clearing rights of other persons
    that may apply to the Work or any use thereof, including without
    limitation any person's Copyright and Related Rights in the Work.
    Further, Affirmer disclaims responsibility for obtaining any necessary
    consents, permissions or other rights required for any use of the
    Work.
 d. Affirmer understands and acknowledges that Creative Commons is not a
    party to this document and has no duty or obligation with respect to
    this CC0 or use of the Work.
Add any additional licenses to that same file if you follow a multi license approach.

3) Use the following shields.io badge for your project to make it shiny:

CC Zero

# in asciidoc
image:https://img.shields.io/badge/license-cc%20zero-000000.svg["CC Zero", link="http://creativecommons.org/publicdomain/zero/1.0/"]

4) Place the following text at the bottom of your README:

To the extent possible under law, the author(s) have dedicated all copyright
and related and neighboring rights to this software to the public domain
worldwide. This software is distributed without any warranty.

You should have received a copy of the CC0 Public Domain Dedication along
with this software. If not, see http://creativecommons.org/publicdomain/zero/1.0/.

5) Create a folder called AUTHORS and place a file called WAIVER with the following content in it:[15]

# Copyright waiver for <LINK_TO_PROJECT>

I dedicate any and all copyright interest in this software to the
public domain. I make this dedication for the benefit of the public at
large and to the detriment of my heirs and successors. I intend this
dedication to be an overt act of relinquishment in perpetuity of all
present and future rights to this software under copyright law.

To the best of my knowledge and belief, my contributions are either
originally authored by me or are derived from prior works which I have
verified are also in the public domain and are not subject to claims
of copyright by other parties.

To the best of my knowledge and belief, no individual, business,
organization, government, or other entity has any copyright interest
in my contributions, and I affirm that I will not make contributions
that are otherwise encumbered.

6) Finally sign the WAIVER, commit it, and push everything together with your first contribution to a project.

$ # sign
$ gpg2 --no-version --armor --sign AUTHORS/WAIVER
$ mv AUTHORS/WAIVER.asc AUTHORS/WAIVER-signed-by-USERNAME.asc

$ # commit
$ git add AUTHORS/WAIVER-signed-by-USERNAME.asc
$ git commit -S AUTHORS/WAIVER-signed-by-USERNAME.asc
The signed WAIVER replaces other alternatives like contributor license agreements (CLAs). It works without requiring any other software, like a centralized registry of developers.

7) Your done, free to do something else with your life now.

Future work will consist of adding the above header to each source file and verifying that GPG signatures are correct and match between signed waiver and signed commit.

w