\usepackage{enumitem}

\usepackage[Conny]{fncychap}

\usepackage[dvips]{graphicx}

\usepackage[verbose, twoside, dvips,

              paperwidth=8.5in, paperheight=11in,

              left=1in, right=1in, top=1.25in, bottom=.75in,

           ]{geometry}

% Make sure hyperref is last in the package list.  Order matters here, See:

%   http://tex.stackexchange.com/questions/77886/fncychap-and-hyperref-messes-up-page-references

\usepackage{hyperref}

\newcommand{\tutorialpartsplit}[2]{#2}

%\input{no-numbers-on-table-of-contents}

\providecommand{\hrefnofollow}[2]{\href{#1}{#2}}

\hypersetup{pdfinfo={Title={Copyleft and the GNU General Public License: A Comprehensive Tutorial and Guide}}}

    \begin{document}

\pagestyle{plain}

\pagenumbering{roman}

\frontmatter

\begin{titlepage}

\begin{center}

{\Huge

{\sc Copyleft and the  \\

GNU General Public License:

\vspace{.25in}

A Comprehensive Tutorial \\

\vspace{.1in}

and Guide

}}

\vfill

{\parindent 0in

\begin{tabbing}

Copyright \= \copyright{} 2003--2005, 2008, 2014--2015, 2018 \hspace{1.mm} \=  \kill

Copyright \> \copyright{} 2018 \>  Chestek Legal. \\

Copyright \> \copyright{} 2014--2015 \>  Anthony K. Sebro, Jr. \\

Copyright \= \copyright{} 2014 \> Denver Gingerich. \\

Copyright \= \copyright{} 2003--2007, 2014 \>  Free Software Foundation, Inc. \\

Copyright \> \copyright{} 2008, 2014 \>  Software Freedom Law Center. \\

\end{tabbing}

\vspace{.3in}

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

adapt, and/or redistribute this work (except

Appendices~\ref{GPLv2-full-text}--\ref{AGPLv3-full-text}) under the terms of the Creative Commons

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

available at \url{https://creativecommons.org/licenses/by-sa/4.0/legalcode}.

Appendices~\ref{GPLv2-full-text}--\ref{AGPLv3-full-text} include copies of the texts of various licenses published

by the FSF, and they are all licensed under the license, ``Everyone is permitted

to copy and distribute verbatim copies of this license document, but changing

it is not allowed.''.  However, those who seek to make modified versions of

those licenses should note the

\href{https://www.gnu.org/licenses/gpl-faq.html#ModifyGPL}{explanation given in the GPL FAQ}.

\vfill

As a public, collaborative project, this Guide is primarily composed of the

many contributions received via its

\href{https://k.copyleft.org/guide/files/master/CONTRIBUTING.md}{public

  contribution process}.  Please

\href{https://k.copyleft.org/guide/changelog/master/}{review its

  Git logs} for full documentation of all contributions, and

Appendix~\ref{third-party-citation-list}

  contains a list of third-party works from which some material herein was

adapted.

The most recent version is

available online at \url{https://copyleft.org/guide/}.  Patches

are indeed welcome to this material.  Sources can be found in the Git

repository at \url{https://k.copyleft.org/guide/}.

}

\end{center}

\end{titlepage}

\tableofcontents

\chapter{Preface}

This tutorial is the culmination of nearly a decade of studying and writing

about software freedom licensing and the GPL\@.  Each part of this tutorial

infringement claims against the non-GPLv2-compliant party and

infringement of the patent, because the implied patent license only

extends to use of the software in accordance with the GPLv2. Further, if

Company \compB{} distributes a competitive advanced Web browsing program 

that is not a modified version of Company \compA{}'s GPL'd Web browsing software

program, Company \compA{} is free to assert its patent against any user or

distributor of that product. It is irrelevant whether Company \compB's

program is also distributed under the GPLv2, as Company \compB{} can not grant

implied licenses to Company \compA's patent.

This result also reassures companies that they need not fear losing their

proprietary value in patents to competitors through the GPLv2 implied patent

license, as only those competitors who adopt and comply with the GPLv2's

terms can benefit from the implied patent license. To continue the

example above, Company \compB{} does not receive a free ride on Company

\compA's patent, as Company \compB{} has not licensed-in and then

redistributed Company A's advanced Web browser under the GPLv2. If Company

\compB{} does do that, however, Company \compA{} still has not lost

competitive advantage against Company \compB{}, as Company \compB{} must then,

when it re-distributes Company \compA's program, grant an implied license

to any of its patents that cover the program. Further, if Company \compB{}

relicenses an improved version of Company A's program, it must do so under

the GPLv2, meaning that any patents it holds that cover the improved version

are impliedly licensed to any licensee. As such, the only way Company

\compB{} can benefit from Company \compA's implied patent license, is if it,

itself, distributes Company \compA's software program and grants an

implied patent license to any of its patents that cover that program.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\chapter{Defending Freedom on Many Fronts}

Chapters~\ref{run-and-verbatim} and~\ref{source-and-binary} presented the

core freedom-defending provisions of GPLv2\@, which are in GPLv2~\S\S0--3.

GPLv2\S\S~4--7 of the GPLv2 are designed to ensure that GPLv2~\S\S0--3 are

not infringed, are enforceable, are kept to the confines of copyright law but

also not trumped by other copyright agreements or components of other

entirely separate legal systems.  In short, while GPLv2~\S\S0--3 are the parts

of the license that defend the freedoms of users and programmers,

GPLv2~\S\S4--7 are the parts of the license that keep the playing field clear

so that \S\S~0--3 can do their jobs.

\section{GPLv2~\S4: Termination on Violation}

\label{GPLv2s4}

GPLv2~\S4 is GPLv2's termination clause.  Upon first examination, it seems

strange that a license with the goal of defending users' and programmers'

freedoms for perpetuity in an irrevocable way would have such a clause.

However, upon further examination, the difference between irrevocability

The GPL is irrevocable in the sense that once a copyright holder grants

rights for someone to copy, modify and redistribute the software under terms

of the GPL, they cannot later revoke that grant.  Since the GPL has no

provision allowing the copyright holder to take such a prerogative, the

license is granted as long as the copyright remains in effect.\footnote{In

  the USA, due to unfortunate legislation, the length of copyright is nearly

  perpetual, even though the Constitution forbids perpetual copyright.} The

copyright holders have the right to relicense the same work under different

licenses (see Section~\ref{Proprietary Relicensing} of this tutorial), or to

stop distributing the GPLv2'd version (assuming GPLv2~\S3(b) was never used),

but they may not revoke the rights under GPLv2 already granted.

In fact, when an entity loses their right to copy, modify and distribute

GPL'd software, it is because of their \emph{own actions}, not that of the

copyright holder.  The copyright holder does not decide when GPLv2~\S4

termination occurs (if ever); rather, the actions of the licensee determine

that.

Under copyright law, the GPL has granted various rights and freedoms to

the licensee to perform specific types of copying, modification, and

redistribution.  By default, all other types of copying, modification, and

redistribution are prohibited.  GPLv2~\S4 says that if you undertake any of

those other types (e.g., redistributing binary-only in violation of GPLv2~\S3),

then all rights under the license --- even those otherwise permitted for

those who have not violated --- terminate automatically.

GPLv2~\S4 makes GPLv2 enforceable.  If licensees fail to adhere to the

license, then they are stuck without any permission under to engage in

activities covered by copyright law.  They must completely cease and desist

from all copying, modification and distribution of the GPL'd software.

At that point, violating licensees must gain the forgiveness of the copyright

holders to have their rights restored.  Alternatively, the violators could

negotiate another agreement, separate from GPL, with the copyright

holder.  Both are common practice, although

\tutorialpartsplit{as discussed in \textit{A Practical Guide to GPL

    Compliance}, there are }{Chapter~\ref{compliance-understanding-whos-enforcing}

  explains further} key differences between these two very different uses of GPL.

\section{GPLv2~\S5: Acceptance, Copyright Style}

\label{GPLv2s5}

GPLv2~\S5 brings us to perhaps the most fundamental misconception and common

confusion about GPLv2\@. Because of the prevalence of proprietary software,

most users, programmers, and lawyers alike tend to be more familiar with

EULAs. EULAs are believed by their authors to be contracts, requiring

formal agreement between the licensee and the software distributor to be

In short, GPLv2~\S6 says that your license for the software is your one and

only copyright license allowing you to copy, modify and distribute the

software.

GPLv2~\S6 is GPLv2's ``automatic downstream licensing''

provision\footnote{This section was substantially expanded for clarity and

  detail in \hyperref[GPLv3s10]{GPLv3~\S10}.}.  Each time you

redistribute a GPL'd program, the recipient automatically receives a license

from each original licensor to copy, distribute or modify the program subject

to the conditions of the license.  The redistributor need not take any

to ensure the downstream recipient's acceptance of the license terms.

This places every copyright holder in the chain of descent of the code

in legal privity, or direct relationship, with every downstream

redistributor.  Two legal effects follow.  First, downstream parties

who remain in compliance have valid permissions for all actions

(including modification and redistribution) even if their immediate upstream

supplier of the software has been terminated for license

violation\footnote{\label{German-reinstatement-footnote} While this is legally true, as a practical matter, a

  failure of ``complete, corresponding source'' (CCS) provisioning by an

  upstream could make it effectively impossible for a downstream party to

  engage in a commercial redistribution pursuant to

  \hyperref[GPLv2s3]{GPLv2~\S3(a--b)}.  (\S~\ref{upstream} in the Compliance

  Guide portion of this tutorial discussed related details.)}.

Downstream's

licensed rights are not dependent on compliance of their upstream, because

their licenses issue directly from the copyright holder.  Second, automatic

termination cannot be cured by obtaining additional copies from an alternate

supplier: the license permissions emanate only from the original licensors,

and if they have automatically terminated permission, no act by any

intermediate license holder can restore those terminated

rights\footnote{While nearly all attorneys and copyleft theorists are in

  agreement on this point, German copyleft legal expert

  \href{http://www.jbb.de/en/attorneys/till-jaeger/}{Till Jaeger}

  vehemently disagrees.  Jaeger's position is as follows: under German

  copyright law, a new copy of GPL'd software is a ``fresh'' license under

  GPL, and if compliance continues from that point further, the violator's

  permissions under copyright law are automatically restored, notwithstanding

  the strict termination provision in \hyperref[GPLv2s4]{GPLv2~\S4}.

  However, in

  practice, this issue is only salient with regard to \hyperref[Proprietary

    Relicensing]{proprietary relicensing} business models, since other copyright

  holders typically formally restore distributions rights once the only

  remaining compliance issue is ``you lost copyright permission due to

  GPLv2~\S4''.  Therefore, the heated debates, which have raged between

  Jaeger and almost everyone else in the copyleft community for nearly a

  decade, regard an almost moot and wholly esoteric legal detail.}.

\section{GPLv2 Irrevocability}

There are two legal theories why a contributor cannot terminate their license

grant. First is an argument that the text of the GPL prevents it; second is

that a contributor would be estopped from succeeding on an infringement claim

for continued use of the code even if it wasn't removed.

\subsection{The text of the GPLv2}

The GPLv2 have several provisions that, when taken together, can be construed

as an irrevocable license from each contributor. First, the GPLv2 says ``by

\emph{modifying} or distributing the Program (or any work based on the Program), you

indicate your acceptance of this License to do so, and all its terms and

conditions for copying, distributing or modifying the Program or works based

on it'' (GPLv2\S5, emphasis added).  A contributor by definition is modifying

the code and therefore has agreed to all the terms in the GPLv2, which

includes the web of mechanisms in the GPLv2 that ensure the code can be used

by all.

More specifically, the downstream license grant says ``the recipient

automatically receives a license from the original licensor to copy,

distribute or modify the Program subject to these terms and conditions.''

(GPLv2\S6). So in this step, the contributor has granted a license to the

downstream, on the condition that the downstream complies with the license

terms.

That license granted to downstream is irrevocable, again provided that the

downstream user complies with the license terms: ``[P]arties who have

received copies, or rights, from you under this License will not have their

licenses terminated so long as such parties remain in full compliance''

(GPLv2\S4).

Thus, anyone downstream of the contributor (which is anyone using the

contributor's code), has an irrevocable license from the contributor. A

contributor may claim to revoke their grant, and subsequently sue for

copyright infringement, but a court would likely find the revocation was

ineffective and the downstream user had a valid license defense to a claim of

infringement.

Nevertheless, for purposes of argument, we will assume that for some

reason the GPLv2 is not enforceable against the contributor\footnote{For

  example, the argument has been made that there may be a failure of

  consideration on the part of the contributor. While \textit{Jacobsen

    v. Katzer}, 535 F.3d 1373 (Fed. Cir. 2008) is accepted as holding that

  there is consideration received by the contributor in a FOSS license, the

  posture of the case was one where the contributor advocated for the theory,

  not against it. The author is not aware of any other decisions that have analyzed

  the question in any depth, so it perhaps could be challenged in the right

  factual situation.}, or that the irrevocable license can be

revoked\footnote{A contract without a definable duration can be terminated on