@@ -40,193 +40,193 @@ license is available at
This is a guide to effective compliance with the GNU General Public
License (GPL) and related licenses. Copyleft advocates
usually seek to assist the community with
GPL compliance cooperatively. This guide focuses on complying from the
start, so that readers can learn to avoid enforcement actions entirely, or, at
least, minimize the negative impact when enforcement actions occur.
This guide introduces and explains basic legal concepts related to the GPL and its
enforcement by copyright holders. It also outlines business practices and
methods that lead to better GPL compliance. Finally, it recommends proper
post-violation responses to the concerns of copyright holders.
\chapter{Background}
Early GPL enforcement efforts began soon after the GPL was written by
Richard M.~Stallman (RMS) in 1989, and consisted of informal community efforts,
often in public Usenet discussions.\footnote{One example is the public
outcry over NeXT's attempt to make the Objective-C front-end to GCC
proprietary. RMS, in fact, handled this enforcement action personally and
the Objective-C front-end is still part of upstream GCC today.} Over the next decade, the Free Software Foundation (FSF),
which holds copyrights in many GNU programs, was the only visible entity
actively enforcing its GPL'd copyrights on behalf of the software freedom
community.
FSF's enforcement
was generally a private process; the FSF contacted violators
confidentially and helped them to comply with the license. Most
violations were pursued this way until the early 2000's.
By that time, Linux-based systems such as GNU/Linux and BusyBox/Linux had become very common, particularly in
embedded devices such as wireless routers. During this period, public
ridicule of violators in the press and on Internet fora supplemented
ongoing private enforcement and increased pressure on businesses to
comply. In 2003, the FSF formalized its efforts into the GPL Compliance
Lab, increased the volume of enforcement, and built community coalitions
to encourage copyright holders to together settle amicably with violators.
Beginning in 2004, Harald Welte took a more organized public enforcement
approach and launched \verb0gpl-violations.org0, a website and mailing
list for collecting reports of GPL violations. On the basis of these
reports, Welte successfully pursued many enforcements in Europe, including
formal legal action. Harald earns the permanent fame as the first copyright
holder to bring legal action in a court regarding GPL compliance.
In 2007, two copyright holders in BusyBox, in conjunction with the
Software Freedom Conservancy (``Conservancy''), filed the first copyright infringement lawsuit
based on a violation of the GPL\@ in the USA. While lawsuits are of course
quite public, the vast majority of Conservancy's enforcement actions
are resolved privately via
cooperative communications with violators. As both FSF and Conservancy have worked to bring
individual companies into compliance, both organizations have encountered numerous
violations resulting from preventable problems such as inadequate
attention to licensing of upstream software, misconceptions about the
GPL's terms, and poor communication between software developers and their
management. This document highlights these problems and describe
best practices to encourage corporate Free Software users to reevaluate their
approach to GPL'd software and avoid future violations.
Both FSF and Conservancy continue GPL enforcement and compliance efforts
for software under the GPL, the GNU Lesser
Public License (LGPL) and other copyleft licenses. In doing so, both organizations have
found that most violations stem from a few common, avoidable mistakes. All copyleft advocates hope to educate the community of
commercial distributors, redistributors, and resellers on how to avoid
violations in the first place, and to respond adequately and appropriately
when a violation occurs.
\chapter{Best Practices to Avoid Common Violations}
\label{best-practices}
Unlike highly permissive licenses (such as the ISC license), which
typically only require preservation of copyright notices, licensees face many
important requirements from the GPL. These requirements are
carefully designed to uphold certain values and standards of the software
freedom community. While the GPL's requirements may initially appear
counter-intuitive to those more familiar with proprietary software
licenses, by comparison, its terms are in fact clear and quite favorable to
licensees. Indeed, the GPL's terms actually simplify compliance when
violations occur.
GPL violations occur (or, are compounded) most often when companies lack sound
practices for the incorporation of GPL'd components into their
internal development environment. This section introduces some best
practices for software tool selection, integration and distribution,
inspired by and congruent with software freedom methodologies. Companies should
establish such practices before building a product based on GPL'd
software.\footnote{This document addresses compliance with GPLv2,
GPLv3, LGPLv2, and LGPLv3. Advice on avoiding the most common
errors differs little for compliance with these four licenses.
\S~\ref{lgpl} discusses the key differences between GPL and LGPL
compliance.}
\section{Evaluate License Applicability}
\label{derivative-works}
Political discussion about the GPL often centers around the ``copyleft''
requirements of the license. Indeed, the license was designed primarily
to embody this licensing feature. Most companies adding non-trivial
features (beyond mere porting and bug-fixing) to GPL'd software (and
thereby invoking these requirements) are already well aware of their
more complex obligations under the license.\footnote{While, there has been much legal
more complex obligations under the license.\footnote{There has been much legal
discussion regarding copyleft and derivative works. In practical
reality, this issue is not relevant to the vast majority of companies
distributing GPL'd software. Those interested in this issue should study
\tutorialpartsplit{\textit{Detailed Analysis of the GNU GPL and Related
Licenses}'s Section on derivative works}{\S~\ref{derivative-works} of
this tutorial}.}
However, experienced GPL enforcers find that few redistributors'
compliance challenges relate directly to the copyleft provisions; this is
particularly true for most embedders. Instead, the distributions of GPL'd
systems most often encountered typically consist of a full operating system
including components under the GPL (e.g., Linux, BusyBox) and components
under the LGPL (e.g., the GNU C Library). Sometimes, these programs have
been patched or slightly improved by direct modification of their sources,
resulting unequivocally in a derivative work. Alongside these programs,
companies often distribute fully independent, proprietary programs,
developed from scratch, which are designed to run on the Free Software operating
system but do not combine with, link to, modify, derive from, or otherwise
create a combined work with
the GPL'd components.\footnote{However, these programs do often combine
with LGPL'd libraries. This is discussed in detail in \S~\ref{lgpl}.}
In the latter case, where the work is unquestionably a separate work of
creative expression, no copyleft provisions are invoked.
Admittedly, a tiny
minority of situations lie outside these two categories, and thus
do involve close questions about derivative and combined works. Those
situations admittedly do require a highly
fact-dependent analysis and cannot be addressed in a general-purpose
document, anyway.
\medskip
Most companies accused of violations lack a basic understanding
of how to comply even in the former straightforward scenario. This document
provides those companies with the fundamental and generally applicable prerequisite knowledge.
For answers to rarer and more complicated legal questions, such as whether
your software is a derivative or combined work of some copylefted software, consult
with an attorney.\footnote{If you would like more information on the
application of derivative works doctrine to software, a detailed legal
discussion is presented in our colleague Dan Ravicher's article,
\textit{Software Derivative Work: A Circuit Dependent Determination} and in
This discussion thus assumes that you have already identified the
``work'' covered by the license, and that any components not under the GPL
(e.g., applications written entirely by your developers that merely happen
to run on a Linux-based operating system) distributed in conjunction with
those works are separate works within the meaning of copyright law and the GPL\@. In
such a case, the GPL requires you to provide complete corresponding
source (CCS)\footnote{For more on CCS, see
Licenses}'s Section on GPLv2~\S2 and GPLv3~\S1.}{\S~\ref{GPLv2s2} and \S~\ref{GPLv3s1} of
for the GPL'd components and your modifications thereto, but not
for independent proprietary applications. The procedures described in
this document address this typical scenario.
\section{Monitor Software Acquisition}
Software engineers deserve the freedom to innovate and import useful
software components to improve products. However, along with that
freedom should come rules and reporting procedures to make sure that you
are aware of what software that you include with your product.
The most typical response to an initial enforcement action is: ``We
didn't know there was GPL'd stuff in there''. This answer indicates
failure in the software acquisition and procurement process. Integration
of third-party proprietary software typically requires a formal
arrangement and management/legal oversight before the developers
incorporate the software. By contrast, developers often obtain and
integrate Free Software without intervention nor oversight. That ease of acquisition, however,
does not mean the oversight is any less necessary. Just as your legal
and/or management team negotiates terms for inclusion of any proprietary
software, they should gently facilitate all decisions to bring Free Software into your
product.
Simple, engineering-oriented rules help provide a stable foundation for
Free Software integration. For example, simply ask your software developers to send an email to a
standard place describing each new Free Software component they add to the system,
and have them include a brief description of how they will incorporate it
into the product. Further, make sure developers use a revision control
system (such as Git or Mercurial), and
store the upstream versions of all software in a ``vendor branch'' or
similar mechanism, whereby they can easily track and find the main version
of the software and, separately, any local changes.
Such procedures are best instituted at your project's launch. Once
chaotic and poorly-sourced development processes begin, cataloging the
presence of GPL'd components becomes challenging.
Such a situation often requires use of a tool to ``catch up'' your knowledge
about what software your product includes. Most commonly, companies choose
some software licensing scanning tool to inspect the codebase. However,