Dispelling Common Legal Myths About Open Source Software Licensing* *But Why they Contain Some Truth Too

  • September 01, 2010
  • Eric Boehm

The use of open source software (OSS) is approaching its third decade but there remain many misconceptions and uncertainties regarding the legal effect of OSS licenses. There are many reasons for this. The chief reason, no doubt, is that while at its heart the concept of OSS is simple, in practice the effects of OSS licensing are complex. One can also blame clumsily drafted OSS licenses, many of which were clearly drafted without legal review. Lastly, there is a dearth of case law which would help in the interpretation of the licenses and clarify the status of OSS licenses at law. 

Uncertainty breeds myths and rumours, and as the use of open source continues to grow, it becomes more imperative that lawyers separate fact from fiction to properly advise their clients when faced with an OSS license. 

The following sets out some of the most common OSS licensing myths, and explains why they are false. But, as will be clear from the analysis below, there is no “one size fits all” answer to any questions regarding OSS, and behind every myth lies some truth. There are many different types of OSS licenses, and each has its own particularities – the answer for one type of OSS license may be different from another. 

1) Open Source Software Is In the Public Domain

a) Why It Is False 

Public domain software is software in which the copyright has expired or the authors have expressly given up their copyrights. Without any copyright, anyone can use the software and is free to use, modify and distribute such software without any legal restriction. The authors of OSS, on the other hand, have not given up their copyrights in the software. Indeed, to make OSS licensing possible, the authors are necessarily relying on their copyrights to impose the OSS licensing terms.

b) Why It Contains Some Truth

Some OSS licenses provide very few restrictions on how software can be used by a licensee, making those licenses akin to public domain regarding ease of use. For example, the Berkeley System Distribution (BSD) License permits a licensee to use BSD-licensed code with very few restrictions, other than attribution of source.1

2) The “Open Source License”

a) Why It Is False

There is no single “open source license”, but many different types, all with their own licensing terms. They range from laconic three paragraph notices to fully fledged licenses equivalent in detail to the standard commercial license. Some are more restrictive and detailed than others. The Open Source Initiative (OSI), a non-profit organization devoted to managing and promoting open source, is one widely recognized arbiter of what constitutes an OSS license. As of May 2010, it has approved 66 different license types (with many variants within those types).2

Roughly speaking, there are four main categories of OSS licenses:

  • General Public License (GPL) type of licenses: These licenses are the most popular licenses, which create a so-called copyleft regime. The overarching intent of the GPL-type license is to allow for an unrestricted right to use, study, copy and modify the licensed software, provided that any modifications to such software also be subject to the same requirements. GPL-type licenses also can have a “viral” effect, as discussed below. It is important to note that even within the GPL itself, there are several competing versions; the latest version (version 3) is quite controversial, which has limited its adoption.3 
  • BSD type of licenses: In contrast to the GPL, BSD-style licenses are quite permissive, and permit most uses of BSD-type licensed software without restriction. Modified versions of BSD-licensed software do not need to be licensed on the same terms as the licensed OSS. As a result, modifications do not have to be distributed in open source form, and can be distributed in object code format only.
  • Mozilla Public License (MPL) type of licenses: The MPL represents a middle ground between the GPL and BSD. A licensee of MPL software can integrate MPL-licensed software into proprietary software, and as with BSD licenses, the licensee does not have make the proprietary software available as OSS. However, in a nod to the GPL-type license, if one wishes to distribute a modified form of the software, it must distribute the modified portion of the MPL-licensed software.
  • “Custom” Licenses: There are many other OSS licenses with their own particular terms, generally as a result of the nature of the type of software being licensed or due to historical quirks in the software’s development. These licenses can take many different forms.


b) Why It Contains Some Truth 

The OSI prescribes a list of criteria that it deems to be the baseline requirements for a license to qualify as an OSS license.4 OSS licenses tend to share some basic characteristics, including

  • at the risk of being blindingly obvious, the software being licensed is distributed with its source code;
  • the source code for any OSS that is redistributed to the public must be made available;
  • there is a right to modify the OSS source code and create new works.

3) Open Source Software Is Free5

a) Why It Is False

It is generally true that OSS is made available at no cost. However, there is no particular restriction that OSS cannot be sold (or resold by a licensee) for a price.6 Indeed, there are many commercial vendors who supply OSS for a fee or who otherwise charge for support, maintenance and other services in connection with the OSS.

b) Why It Contains Some Truth

For software to be “open source”, it must be distributed with its source code or with a “well-publicized means of obtaining the source code for no more than a reasonable reproduction cost preferably, downloading via the Internet without charge.”7 Once one licensee has obtained the source code, that licensee will have access to the source code without any restrictions on further distribution, whether for free or at a price. Therefore, whether or not a licensee has paid for the OSS in the first instance, the source code can always be publicly available for free.

4) Open Source Software Is by Its Nature Viral

a) Why It Is False 

The greatest controversy in the OSS movement stems from the so-called “viral” effect of some OSS licenses. “Viral” refers to the general licensing approach that any program derived from a program licensed under a viral OSS license will itself necessarily be subject to such license, whether or not the programmer intended this to happen.8 As a result, if a programmer integrates even a small amount of code licensed under the GPL into an otherwise closed, proprietary software base, then the whole program may become OSS subject to the viral license.9 The poster child for viral effects is the GPL, although there are many other licenses with similar terms. 

This viral nature is not a necessary element of OSS, and many OSS licenses approved by the OSI do not result in such viral effect (including notably BSD-type licenses), or such effect is much more limited (as with the MPL-type license).

b) Why It Contains Some Truth 

Studies have shown that about 60% of all OSS packages released under an OSS license are released under the GPL,10 and the GPL is not the only viral OSS license. As a result, the odds are good that any particular OSS will indeed have viral license terms.


In Part 2 (to be published in late Fall 2010), we will continue our list and discuss the following myths (and their grains of truth): (5) open source licenses are unenforceable, (6) the best policy is a ‘no open source’ policy, (7) if I avoid distribution, then I can make any changes I want and I won’t have to make it publicly available, and (8) OSS is provided without representations and warranties.



1 The BSD License. Open Source Initiative [opensource.org/licenses/bsd-license.php, last accessed April 28, 2010]. 
2 Open Source Initiative, [www.opensource.org/licenses, last accessed April 28, 2010].
3 For a more detailed discussion, see Eric Boehm, “An Open Source Community Divided: Is GPLv3 a Blind Alley or a Path to the Future?” Internet and E-Commerce Law in Canada (2008-2009) 9 I.E.C.L.C., Vol. 9, No. 6, October 2008.
4 This definition is not without its detractors. The Free Software Foundation (which primarily advocates for GPL-style OSS licenses), for one, objects philosophically to some of the terms, since they, among other things, permit taking code private, which is contrary to the GPL-style license [see www.gnu.org/philosophy/categories.html, last accessed April 28, 2010].
5 This paper does not discuss the various philosophical notions of the word “free” that are debated ad nauseum in the open source community. “Free”, in the context of this paper, means “no cost”.
6 The OSI, in its definition of whether software can be called “open source”, states, in section 1: “The license shall not restrict any party from selling or giving away the software as a component of an aggregate software distribution containing programs from several different sources. The license shall not require a royalty or other fee for such sale.” [opensource.org/docs/osd, last accessed April 28, 2010].
7 OSI Open Source Definition, s. 2.
8 See, for example, section 6 of the GNU General Public License. Free Software Foundation fsf.org/licenses, last accessed April 28, 2010].
9 Ibid., s. 2.
10 Black Duck Software Open Source License Resource Center [www.blackducksoftware.com/oss, last accessed April 28, 2010].