% compliance-guide.tex                            -*- LaTeX -*-

\part{A Practical Guide to GPL Compliance}

\label{gpl-compliance-guide}

{\parindent 0in

This part is: \\

\begin{tabbing}

Copyright \= \copyright{} 2014 \= \hspace{.2in} Bradley M. Kuhn. \\

Copyright \= \copyright{} 2014 \= \hspace{.2in} Free Software Foundation, Inc. \\

Copyright \> \copyright{} 2008 \> \hspace{.2in} Software Freedom Law Center. \\

\end{tabbing}

\vspace{1in}

\begin{center}

Authors of this part are: \\

Bradley M. Kuhn \\

Aaron Williamson \\

Karen M. Sandler \\

\vspace{1in}

Copy editors of this part include: \\

Martin Michlmayr

\vspace{3in}

The copyright holders of this part hereby grant the freedom to copy, modify,

convey, Adapt, and/or redistribute this work under the terms of the Creative

Commons Attribution Share Alike 4.0 International License.  A copy of that

license is available at

\end{center}

}

\bigskip

\chapter*{Executive Summary}

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

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{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 combined work issues in copyleft.

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,

and thus the result is unequivocally a modified version.  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.

The core compliance issue faced, thus, in such a situation, is not an discussion of what is or is not a

combined, derivative, and/or modified version of the work, but rather, issues related to distribution and

conveyance of binary works based on GPL'd source, but without Complete,

Corresponding Source.  This tutorial therefore focuses primarily on that issue.

Admittedly, a tiny

minority of compliance situations relate to question of derivative,

combined, or modified versions of the work.  Those

situations are so rare, and the details from situation to situation differ

greatly.  Thus, such situations require a highly

fact-dependent analysis and cannot be addressed in a general-purpose

document such as this one.

``Corresponding Source'' code for the binary distribution, which includes

the source code from which the binary was produced.  This abbreviated and

simplified definition is sufficient for the binary distribution discussion

in this section, but you may wish to refer back to this section after

reading the thorough discussion of ``Corresponding Source'' that appears

in \S~\ref{corresponding-source}.

\subsection{Option (a): Source Alongside Binary}

GPLv2~\S~3(a) and v3~\S~6(a) embody the easiest option for providing

source code: including Corresponding Source with every binary

distribution.  While other options appear initially less onerous, this

option invariably minimizes potential compliance problems, because when

you distribute Corresponding Source with the binary, \emph{your GPL

  obligations are satisfied at the time of distribution}.  This is not

true of other options, and for this reason, we urge you to seriously

consider this option.  If you do not, you may extend the duration of your

obligations far beyond your last binary distribution.

Compliance under this option is straightforward.  If you ship a product

that includes binary copies of GPL'd software (e.g., in firmware, or on a

hard drive, CD, or other permanent storage medium), you can store the

Corresponding Source alongside the binaries.  Alternatively, you can

include the source on a CD or other removable storage medium in the box

containing the product.

GPLv2 refers to the various storage mechanisms as ``medi[a] customarily

used for software interchange''.  While the Internet has attained primacy

as a means of software distribution where super-fast Internet connections

are available, GPLv2 was written at a time when downloading software was

not practical (and was often impossible).  For much of the world, this

condition has not changed since GPLv2's publication, and the Internet

still cannot be considered ``a medium customary for software

interchange''.  GPLv3 clarifies this matter, requiring that source be

``fixed on a durable physical medium customarily used for software

interchange''.  This language affirms that option (a) requires binary

redistributors to provide source on a physical medium.

Please note that while selection of option (a) requires distribution on a

physical medium, voluntary distribution via the Internet is very useful.  This

is discussed in detail in \S~\ref{offer-with-internet}.

\subsection{Option (b): The Offer}

\label{offer-for-source}

Many distributors prefer to ship only an offer for source with the binary

distribution, rather than the complete source package.  This

option has value when the cost of source distribution is a true

per-unit cost.  For example, this option might be a good choice for

embedded products with permanent storage too small to fit the source, and

which are not otherwise shipped with a CD but \emph{are} shipped with a

manual or other printed material.

However, this option increases the duration of your obligations

dramatically.  An offer for source must be good for three full years from

your last binary distribution (under GPLv2), or your last binary or spare

part distribution (under GPLv3).  Your source code request and

provisioning system must be designed to last much longer than your product

life cycle.

In addition, if you are required to comply with the terms of GPLv2, you

{\bf cannot} use a network service to provide the source code.  For GPLv2,

the source code offer is fulfilled only with physical media.  This usually

means that you must continue to produce an up-to-date ``source code CD''

for years after the product's end-of-life.

\label{offer-with-internet}

Under GPLv2, it is acceptable and advisable for your offer for source code

to include an Internet link for downloadable source \emph{in addition} to

offering source on a physical medium.  This practice enables those with

fast network connections to get the source more quickly, and typically

decreases the number of physical media fulfillment requests.

(GPLv3~\S~6(b) permits provision of source with a public

network-accessible distribution only and no physical media.  We discuss

this in detail at the end of this section.)

The following is a suggested compliant offer for source under GPLv2 (and

is also acceptable for GPLv3) that you would include in your printed

materials accompanying each binary distribution:

\begin{quote}

The software included in this product contains copyrighted software that

is licensed under the GPL\@.  A copy of that license is included in this

document on page $X$\@.  You may obtain the complete Corresponding Source

code from us for a period of three years after our last shipment of this

product, which will be no earlier than 2011-08-01, by sending a money

order or check for \$5 to: \\

GPL Compliance Division \\

Our Company \\

Any Town, US 99999 \\

\\

Please write ``source for product $Y$'' in the memo line of your

payment.

You may also find a copy of the source at

This offer is valid to anyone in receipt of this information.

\end{quote}

There are a few important details about this offer.  First, it requires a

copying fee.  GPLv2 permits ``a charge no more than your cost of

physically performing source distribution''.  This fee must be reasonable.

If your cost of copying and mailing a CD is more than around \$10, you

should perhaps find a cheaper CD stock and shipment method.  It is simply

not in your interest to try to overcharge the community.  Abuse of this

provision in order to make a for-profit enterprise of source code

provision will likely trigger enforcement action.

Second, note that the last line makes the offer valid to anyone who

requests the source.  This is because v2~\S~3(b) requires that offers be

``to give any third party'' a copy of the Corresponding Source.  GPLv3 has

a similar requirement, stating that an offer must be valid for ``anyone

who possesses the object code''.  These requirements indicated in

v2~\S~3(c) and v3~\S~6(c) are so that noncommercial redistributors may

pass these offers along with their distributions.  Therefore, the offers

must be valid not only to your customers, but also to anyone who received

a copy of the binaries from them.  Many distributors overlook this

requirement and assume that they are only required to fulfill a request

from their direct customers.

The option to provide an offer for source rather than direct source

distribution is a special benefit to companies equipped to handle a

fulfillment process.  GPLv2~\S~3(c) and GPLv3~\S~6(c) avoid burdening

noncommercial, occasional redistributors with fulfillment request

obligations by allowing them to pass along the offer for source as they

received it.

Note that commercial redistributors cannot avail themselves of the option

(c) exception, and so while your offer for source must be good to anyone

who receives the offer (under v2) or the object code (under v3), it

\emph{cannot} extinguish the obligations of anyone who commercially

redistributes your product.  The license terms apply to anyone who

distributes GPL'd software, regardless of whether they are the original

distributor.  Take the example of Vendor $V$, who develops a software

platform from GPL'd sources for use in embedded devices.  Manufacturer $M$

contracts with $V$ to install the software as firmware in $M$'s device.

$V$ provides the software to $M$, along with a compliant offer for source.

In this situation, $M$ cannot simply pass $V$'s offer for source along to

its customers.  $M$ also distributes the GPL'd software commercially, so

$M$ too must comply with the GPL and provide source (or $M$'s \emph{own}

offer for source) to $M$'s customers.

This situation illustrates that the offer for source is often a poor

choice for products that your customers will likely redistribute.  If you

include the source itself with the products, then your distribution to

your customers is compliant, and their (unmodified) distribution to their

customers is likewise compliant, because both include source.  If you

include only an offer for source, your distribution is compliant but your

customer's distribution does not ``inherit'' that compliance, because they

have not made their own offer to accompany their distribution.

The terms related to the offer for source are quite different if you

distribute under GPLv3.  Under v3, you may make source available only over

a network server, as long as it is available to the general public and

remains active for three years from the last distribution of your product

or related spare part.  Accordingly, you may satisfy your fulfillment

obligations via Internet-only distribution.  This makes the ``offer for

source'' option less troublesome for v3-only distributions, easing

compliance for commercial redistributors.  However, before you switch to a

purely Internet-based fulfillment process, you must first confirm that you

can actually distribute \emph{all} of the software under GPLv3.  Some

programs are indeed licensed under ``GPLv2, \emph{or any later version}''

(often abbreviated ``GPLv2-or-later'').  Such licensing gives you the

option to redistribute under GPLv3.  However, a few popular programs are

only licensed under GPLv2 and not ``or any later version''

(``GPLv2-only'').  You cannot provide only Internet-based source request

fulfillment for the latter programs.

If you determine that all GPL'd works in your whole product allow upgrade

to GPLv3 (or were already GPLv3'd to start), your offer for source may be

as simple as this:

\begin{quote}

The software included in this product contains copyrighted software that

is licensed under the GPLv3\@.  A copy of that license is included in this

document on page $X$\@.  You may obtain the complete Corresponding Source

code from us for a period of three years after our last shipment of this

product and/or spare parts therefor, which will be no earlier than

2011-08-01, on our website at

\end{quote}

\medskip

Under both GPLv2 and GPLv3, source offers must be accompanied by a copy of

the license itself, either electronically or in print, with every

distribution.

Finally, it is unacceptable to use option (b) merely because you do not have

Corresponding Source ready.  We find that some companies choose this option

because writing an offer is easy, but producing a source distribution as

an afterthought to a hasty development process is difficult.  The offer

for source does not exist as a stop-gap solution for companies rushing to

market with an out-of-compliance product.  If you ship an offer for source

with your product but cannot actually deliver \emph{immediately} on that

offer when your customers request it, you should expect an enforcement

action.

\subsection{Option (c): Noncommercial Offers}

As discussed in the last section, GPLv2~\S~3(c) and GPLv3~\S~6(c) apply

only to noncommercial use.  These options are not available to businesses

distributing GPL'd software.  Consequently, companies that redistribute

software packaged for them by an upstream vendor cannot merely pass along

the offer they received from the vendor; they must provide their own offer

or corresponding source to their distributees.  We talk in detail about

upstream software providers in \S~\ref{upstream}.

\subsection{Option 6(d) in GPLv3: Internet Distribution}

Under GPLv2, your formal provisioning options for Corresponding Source

ended with \S~3(c).  But even under GPLv2, pure Internet source

distribution was a common practice and generally considered to be

compliant.  GPLv2 mentions Internet-only distribution almost as aside in

the language, in text at the end of the section after the three

provisioning options are listed.  To quote that part of GPLv2~\S~3:

\begin{quote}

If distribution of executable or object code is made by offering access to

copy from a designated place, then offering equivalent access to copy the

source code from the same place counts as distribution of the source code,

even though third parties are not compelled to copy the source along with

the object code.

\end{quote}

When that was written in 1991, Internet distribution of software was the

exception, not the rule.  Some FTP sites existed, but generally software

was sent on magnetic tape or CDs.  GPLv2 therefore mostly assumed that

binary distribution happened on some physical media.  By contrast,

GPLv3~\S~6(d) explicitly gives an option for this practice that the

community has historically considered GPLv2-compliant.

Thus, you may fulfill your source-provision obligations by providing the

source code in the same way and from the same location.  When exercising

this option, you are not obligated to ensure that users download the

source when they download the binary, and you may use separate servers as

needed to fulfill the requests as long as you make the source as

accessible as the binary.  However, you must ensure that users can easily

find the source code at the time they download the binary. GPLv3~\S~6(d)

thus clarifies a point that has caused confusion about source provision in

v2.  Indeed, many such important clarifications are included in v3 which

together provide a compelling reason for authors and redistributors alike

to adopt GPLv3.

\subsection{Option 6(e) in GPLv3: Software Torrents}

Peer-to-peer file sharing arose well after GPLv2 was written, and does not

easily fit any of the v2 source provision options.  GPLv3~\S~6(e)

addresses this issue, explicitly allowing for distribution of source and

binary together on a peer-to-peer file sharing network.  If you distribute

solely via peer-to-peer networks, you can exercise this option.  However,

peer-to-peer source distribution \emph{cannot} fulfill your source

provision obligations for non-peer-to-peer binary distributions.  Finally,

you should ensure that binaries and source are equally seeded upon initial

peer-to-peer distribution.

\section{Preparing Corresponding Source}

\label{corresponding-source}

Most enforcement cases involve companies that have unfortunately not

implemented procedures like our \S~\ref{best-practices} recommendations

and have no source distribution arranged at all.  These companies must

work backwards from a binary distribution to come into compliance.  Our

recommendations in \S~\ref{best-practices} are designed to make it easy to

construct a complete and Corresponding Source release from the outset.  If

you have followed those principles in your development, you can meet the

following requirements with ease.  If you have not, you may have

substantial reconstruction work to do.

\subsection{Assemble the Sources}

For every binary that you produce, you should collect and maintain a copy

of the sources from which it was built.  A large system, such as an

embedded firmware, will probably contain many GPL'd and LGPL'd components

for which you will have to provide source.  The binary distribution may

also contain proprietary components which are separate and independent

works that are covered by neither the GPL nor LGPL\@.

%      Tutorial Text for the Detailed Study and Analysis of GPL and LGPL course

% License: CC-By-SA-4.0

% The copyright holders hereby grant the freedom to copy, modify, convey,

% Adapt, and/or redistribute this work under the terms of the Creative

% Commons Attribution Share Alike 4.0 International License.

% This text is distributed in the hope that it will be useful, but

% WITHOUT ANY WARRANTY; without even the implied warranty of

% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

% You should have received a copy of the license with this document in

% a file called 'CC-By-SA-4.0.txt'.  If not, please visit

% https://creativecommons.org/licenses/by-sa/4.0/legalcode to receive

% the license text.

\part{Case Studies in GPL Enforcement}

{\parindent 0in

This part is: \\

\begin{tabbing}

Copyright \> \copyright{} 2014 \>  Bradley M. Kuhn. \\

Copyright \= \copyright{} 2014 \= \hspace{.2in} Denver Gingerich \\

Copyright \= \copyright{} 2003, 2004, 2014 \= \hspace{.2in} Free Software Foundation, Inc. \\

\end{tabbing}

\vspace{1in}

\begin{center}

Authors of this part are: \\

Bradley M. Kuhn \\

John Sullivan

\vspace{3in}

Copy editors of this part include: \\

Martin Michlmayr

\vspace{3in}

The copyright holders hereby grant the freedom to copy, modify, convey,

Adapt, and/or redistribute this work under the terms of the Creative Commons

Attribution Share Alike 4.0 International License.  A copy of that license is

\end{center}

}

% =====================================================================

% START OF SECOND DAY SEMINAR SECTION

% =====================================================================

\chapter*{Preface}

This one-day course presents the details of five different GPL

compliance cases handled by FSF's GPL Compliance Laboratory. Each case

offers unique insights into problems that can arise when the terms of

the GPL are not properly followed, and how diplomatic negotiation between

the violator and the copyright holder can yield positive results for

both parties.

Attendees should have successfully completely the course, a ``Detailed

Study and Analysis of the GPL and LGPL,'' as the material from that

course forms the building blocks for this material.

This course is of most interest to lawyers who have clients or

employers that deal with Free Software on a regular basis. However,

technical managers and executives whose businesses use or distribute

Free Software will also find the course very helpful.

\bigskip

These course materials are merely a summary of the highlights of the

course presented. Please be aware that during the actual GPL course, class

discussion supplements this printed curriculum. Simply reading it is

not equivalent to attending the course.

%FIXME-LATER: write these

%\chapter{Not All GPL Enforcement is Created Equal}

%\section{For-Profit Enforcement}

%\section{Community and Non-Profit Enforcement}

\chapter{Overview of Community Enforcement}

The GPL is a Free Software license with legal teeth. Unlike licenses like

the X11-style or various BSD licenses, the GPL (and by extension, the LGPL) is

designed to defend as well as grant freedom. We saw in the last course

that the GPL uses copyright law as a mechanism to grant all the key freedoms

essential in Free Software, but also to ensure that those freedoms

propagate throughout the distribution chain of the software.

\section{Termination Begins Enforcement}

As we have learned, the assurance that Free Software under the GPL remains

Free Software is accomplished through various terms of the GPL: \S 3 ensures

that binaries are always accompanied with source; \S 2 ensures that the

sources are adequate, complete and usable; \S 6 and \S 7 ensure that the

license of the software is always the GPL for everyone, and that no other

legal agreements or licenses trump the GPL. It is \S 4, however, that ensures

that the GPL can be enforced.

Thus, \S 4 is where we begin our discussion of GPL enforcement. This

clause is where the legal teeth of the license are rooted. As a copyright

license, the GPL governs only the activities governed by copyright law ---

copying, modifying and redistributing computer software. Unlike most

copyright licenses, the GPL gives wide grants of permission for engaging with

these activities. Such permissions continue, and all parties may exercise

them until such time as one party violates the terms of the GPL\@. At the

moment of such a violation (i.e., the engaging of copying, modifying or

redistributing in ways not permitted by the GPL) \S 4 is invoked. While other

parties may continue to operate under the GPL, the violating party loses their

rights.

Specifically, \S 4 terminates the violators' rights to continue

engaging in the permissions that are otherwise granted by the GPL\@.

Effectively, their rights revert to the copyright defaults ---

no permission is granted to copy, modify, nor redistribute the work.

Meanwhile, \S 5 points out that if the violator has no rights under

the GPL, they are prohibited by copyright law from engaging in the

activities of copying, modifying and distributing. They have lost

these rights because they have violated the GPL, and no other license

gives them permission to engage in these activities governed by copyright law.

\section{Ongoing Violations}

In conjunction with \S 4's termination of violators' rights, there is

one final industry fact added to the mix: rarely does one engage in a

single, solitary act of copying, distributing or modifying software.

Almost always, a violator will have legitimately acquired a copy of a

GPL'd program, either making modifications or not, and then begun

distributing that work. For example, the violator may have put the

software in boxes and sold them at stores. Or perhaps the software

was put up for download on the Internet. Regardless of the delivery

mechanism, violators almost always are engaged in {\em ongoing\/}

violation of the GPL\@.

In fact, when we discover a GPL violation that occurred only once --- for

example, a user group who distributed copies of a GNU/Linux system without

source at one meeting --- we rarely pursue it with a high degree of