The Open Works License

The Open Works License, henceforth also referred to as the OWL, was developed to fill the need for a copyfree license that does not limit itself in its intended application to software or any other particular content form. It is intended to be understandable to the layman while still providing adequate legal protection and clarity for the terms of the license.

If you would prefer a license with a patent clause, have a look at the COIL.

In Brief:

This license is intended to roughly mimic the "public domain" (a legal concept particular to certain jurisdictions) while ensuring that no restrictive copyright claims are enforced. Two important points distinguish this license from the public domain:

  1. Unlike the OWL, modifications of a work in the public domain can be subject to assertions of copyright restriction by the entity that holds the copyright of the modifications that resulted in the modified work. This means that the only version of something released into the public domain that is guaranteed by law to be available in perpetuity under the terms of that release is the original, unmodified version. The OWL is intended to ensure that direct modifications of the work will also be available under its terms, while still allowing the covered works to be used within larger works that may not employ the same license, and allowing original material in derivative works to be distributed under different terms as a means of ensuring license incompatibilities will not arise as they do for copyleft or share-alike license terms.

  2. Unlike the public domain, anything licensed under the terms of the OWL should be subject to its terms, or close approximations thereof, even in jurisdictions that do not recognize the legal concept of the public domain, as long as it recognizes common concepts of copyright. The OWL is intended to achieve this without imposing restrictions or conditions that cannot exist without copyright enforcement, to the extent practical under common copyright law regimes.

In general, you may redistribute, modify, copy, use, fold, spindle, and mutilate any work covered by the OWL as desired, provided you include the text of the OWL with it, granting any recipients of the work (modified or unmodified) the same rights and privileges.


As with any copyfree license, the OWL is designed so that it should be effectively self-enforcing in the general case. This is because it serves more properly as a defense of the possessor against restrictive copyright enforcement than an assertion of legal rights for the copyright holder. Even if, in violation of the license terms, a distributor fails to provide notice of the OWL's terms, the fact that the material was initially distributed under these terms should allow use of the OWL as defense against spurious claims of copyright infringement by license violating distributors.

In cases of plagiarism, which should also apply to cases of redistribution of the work (modified or unmodified) without notice of the OWL's terms, the appropriate jurisdiction's legal provisions for addressing such misrepresentation should be sufficient to settle disputes over licensing, even if effective enforcement of open source license terms are impractical due to the difficulty of proving material damage in civil proceedings.

The above is not intended as legal advice. It merely serves to explain the intent of the design of the Open Works License with regard to enforcement options.


In short, the intent of the Open Works License is as follows: The materials as you originally receive them under the terms of the OWL must keep the text of the OWL with them. Direct alterations to those materials will also be covered by the terms of the OWL. At any point where a clear division between old material and new material exists (such as separate files, different parts of a file, et cetera), different materials may be distributed under different licenses as long as distinct license notice is maintained. Thus, if you receive a single software source file that is distributed under the terms of the OWL, add three new functions to the end of the file, and modify the main routine to use those functions, you could place the text of the OWL after the original (and modified) material with a note saying that the preceding source is covered by the OWL, then place a separate license below it but above the new functions with a note saying that the following source is covered by the other license to remain compliant with the OWL.

Other measures may be taken to differentiate between Open Works Licensed material and material distributed under a different license in the same distribution of a larger work, such as license identifying notes within files and separate license files included with the distribution, or a single COPYING file containing explicit listings of which files are subject to which licenses, for instance. The key factor to consider is that clear identification of the applicability of the OWL to the materials you originally received under the terms of the OWL, including modified versions where the modifications cannot reasonably be separated from the rest of the materials distributed with the OWL (such as minor copy edits, bug fixes, or function calls mixed with the rest of a source file).

The OWL is designed to serve as a means of encouraging the distribution and use of the covered material -- even within larger projects that are distributed under the terms of other licenses. Weak heritability copyfree licenses such as the OWL are suitable for works whose widespread adoption and use are desirable, such as in cases where the concept or work is more important to be shared widely than the license terms themselves, or when it is believed that strong license terms heritability may hinder the adoption or distribution of the work significantly by virtue of its "viral" nature.

Its use is also encouraged for those who do not much care what happens to their works once released, who wish such intent to be made clear for any form of copyrightable content in any jurisdiction.

As with the Enforcement section, the above is not intended as legal advice. It merely serves to explain the intent of the design of the Open Works License with regard to license heritability.


Early development versions of this license used the name Public Distribution License. The unfortunate name clash between the Public Distribution License (or PDL) and Sun Microsystems' Public Documentation License (also known as the PDL) prompted the change of the name from PDL to OWL. The fortunate association of the new acronym with a nocturnal avian regarded as a symbol of wisdom is really just a happy accident.

For historical (or hysterical) reasons, the PDL Website will remain accessible in its original form.