% gpl-lgpl.tex                                                  -*- LaTeX -*-

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

%

% Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.

% Copyright (C) 2014             Bradley M. Kuhn

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\newcommand{\defn}[1]{\emph{#1}}

\part{Detailed Analysis of the GNU GPL and Related Licenses}

\begin{center}

{\parindent 0in

This part is: \\

\begin{tabbing}

Copyright \= \copyright{} 2003, 2004, 2005 \= \hspace{.2in} Free Software Foundation, Inc. \\

\end{tabbing}

Authors of this Part Are: \\

Bradley M. Kuhn \\

David ``Novalis'' Turner \\

Daniel B. Ravicher \\

John Sullivan

\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

\verb=https://creativecommons.org/licenses/by-sa/4.0/legalcode=.  }

\end{center}

\bigskip

This part of the tutorial gives a comprehensive explanation of the most

To successfully benefit of from this part of the tutorial, readers should

tutorial is of most interest to lawyers, software developers and managers who

\begin{itemize}

  \item The differences between GPLv2 and GPLv3.

  \item The redistribution options under the GPLv2 and GPLv3.

  \item The basics of the Lesser GPLv2.1 and Lesser GPLv3, and how they

    differs from the GPLv2 and GPLv3, respectively.

\end{itemize}

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% END OF ABSTRACTS SECTION

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% START OF DAY ONE COURSE

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\chapter{What Is Software Freedom?}

Consideration of the GNU General Public License (herein, abbreviated as

\defn{GNU GPL} or just \defn{GPL}) must begin by first considering the broader

world of Free Software. The GPL was not created from a void, rather,

it was created to embody and defend a set of principles that were set

forth at the founding of the GNU project and the Free Software Foundation

(FSF)---the organization that upholds, defends and promotes the philosophy

of software freedom. A prerequisite for understanding both of the popular

versions of GPL (GPLv2 and GPLv3) and their

terms and conditions is a basic understanding of the principles behind it.

The GPL family of licenses are unlike almost all other software licenses in that it is

designed to defend and uphold these principles.

\section{The Free Software Definition}

\label{Free Software Definition}

The Free Software Definition is set forth in full on FSF's Web site at

\verb0http://www.fsf.org/0 \verb0philosophy/free-sw.html0. This section

presents an abbreviated version that will focus on the parts that are most

pertinent to the terms of the GPL\@.

A particular program is Free Software if it grants a particular user of

that program, the following freedoms:

\begin{itemize}

\item The freedom to run the program for any purpose

\item The freedom to change and modify the program

\item The freedom to copy and share the program

\item The freedom to share improved versions of the program

\end{itemize}

The focus on ``a particular user'' is very pertinent here. It is not

uncommon for the same version of a specific program to grant these

freedoms to some subset of its user base, while others have none or only

some of these freedoms. Section~\ref{Proprietary Relicensing} talks in

detail about how this can happen even if a program is released under the

GPL\@.

Some people refer to software that gives these freedoms as ``Open

Source.''  Besides having a different political focus than those who

call it Free Software,\footnote{The political differences between the

  Free Software Movement and the Open Source Movement are documented

  on FSF's Web site at {\tt

    http://www.fsf.org/licensing/essays/free-software-for-freedom.html}.}

those who call the software ``Open Source'' are focused on a side

issue.  User access to the source code of a program is a prerequisite

to make use of the freedom to modify. However, the important issue is

what freedoms are granted in the license of that source code.

Microsoft's ``Shared Source'' program, for example, gives various

types of access to source code, but almost none of the freedoms

described in this section.

One key issue central to these freedoms is that there are no

restrictions on how these freedoms can be exercised. Specifically, users

and programmers can exercise these freedoms noncommercially or

commercially. Licenses that grant these freedoms for noncommercial

activities but prohibit them for commercial activities are considered

non-Free.

In general, software for which most or all of these freedoms are

restricted in any way is called ``non-Free Software.''  Typically, the

term ``proprietary software'' is used more or less interchangeably with

``non-Free Software.''  Personally, I tend to use the term ``non-Free

Software'' to refer to noncommercial software that restricts freedom

(such as ``shareware'') and ``proprietary software'' to refer to

commercial software that restricts freedom (such as nearly all of

Microsoft's and Oracle's offerings).

The remainder of this section considers each of the four freedoms in

detail.

\subsection{The Freedom to Run}

For a program to be Free Software, the freedom to run the program must

be completely unrestricted. This means any use for software the user

can come up with must be permitted. Perhaps, for example, the user

has discovered an innovative use for a particular program, one

that the programmer never could have predicted. Such a use must not

be restricted.

It was once rare that this freedom was restricted by even proprietary

software; today it is not so rare. Most End User Licensing Agreements

(EULAs) that cover most proprietary software restrict some types of

use.  For example, some versions of Microsoft's FrontPage software

prohibit use of the software to create Web sites that generate

negative publicity for Microsoft. Free Software has no such

restrictions; everyone is free to use Free Software for any purpose

whatsoever.

\subsection{The Freedom to Change and Modify}

Free Software programs allow users to change, modify and adapt the

software to suit their needs. Access to the source code and related build

scripts are an essential part of this freedom. Without the source code

and the ability to build the binary applications from that source, the

freedom cannot be properly exercised.

Programmers can take direct benefit from this freedom, and often do.

However, this freedom is also important to users who are not programmers.

Users must have the right to exercise this freedom indirectly in both

commercial and noncommercial settings. For example, users often seek

noncommercial help with the software on email lists and in users groups.

When they find such help, they must have the freedom to recruit

programmers who might altruistically assist them to modify their software.

The commercial exercise of this freedom is also essential for users. Each

user, or group of users, must have the right to hire anyone they wish in a

competitive free market to modify and change the software. This means

that companies have a right to hire anyone they wish to modify their Free

Software. Additionally, such companies may contract with other companies

to commission software modification.

\subsection{The Freedom to Copy and Share}

Users may share Free Software in a variety of ways. Free Software

advocates work to eliminate a fundamental ethical dilemma of the software

age: choosing between obeying a software license, and friendship (by

giving away a copy of a program to your friend who likes the software you are

using). Free Software licenses, therefore, must permit this sort of

altruistic sharing of software among friends.

The commercial environment must also have the benefits of this freedom.

Commercial sharing typically takes the form of selling copies of Free

Software. Free Software can be sold at any price to anyone. Those who

redistribute Free Software commercially have the freedom to selectively

distribute (you can pick your customers) and to set prices at any level

the redistributor sees fit.

It is true that many people get copies of Free Software very cheaply (and

sometimes without charge). The competitive free market of Free Software

tends to keep prices low and reasonable. However, if someone is willing

to pay a billion dollars for one copy of the GNU Compiler Collection, such

a sale is completely permitted.

Another common instance of commercial sharing is service-oriented

distribution. For example, a distribution vendor may provide immediate

security and upgrade distribution via a special network service. Such

distribution is completely permitted for Free Software.

(Section~\ref{Business Models} of this tutorial talks in detail about

various Free Software business models that take advantage of the freedom

to share commercially.)

\subsection{The Freedom to Share Improvements}

The freedom to modify and improve is somewhat empty without the freedom to

share those improvements. The Free Software community is built on the

pillar of altruistic sharing of improved Free Software. Inevitably, a

Free Software project sprouts a mailing list where improvements are shared

freely among members of the development community. Such noncommercial

sharing must be permitted for Free Software to thrive.

Commercial sharing of modified Free Software is equally important.

For commercial support to exist in a competitive free market, all

developers --- from single-person contractors to large software

companies --- must have the freedom to market their services as

improvers of Free Software. All forms of such service marketing must

be equally available to all.

For example, selling support services for Free Software is fully

permitted. Companies and individuals can offer themselves as ``the place

to call'' when software fails or does not function properly. For such a

service to be meaningful, the entity offering that service must have the

right to modify and improve the software for the customer to correct any

problems that are beyond mere user error.

Entities must also be permitted to make available modified versions of

Free Software. Most Free Software programs have a ``standard version''

that is made available from the primary developers of the software.

However, all who have the software have the ``freedom to fork'' --- that

is, make available nontrivial modified versions of the software on a

permanent or semi-permanent basis. Such freedom is central to vibrant

developer and user interaction.

Companies and individuals have the right to make true value-added versions

of Free Software. They may use freedom to share improvements to

distribute distinct versions of Free Software with different functionality

and features. Furthermore, this freedom can be exercised to serve a

disenfranchised subset of the user community. If the developers of the

standard version refuse to serve the needs of some of the software's

users, other entities have the right to create a long- or short-lived fork

to serve that sub-community.

\section{How Does Software Become Free?}

The last section set forth the freedoms and rights respected by Free

Software. It presupposed, however, that such software exists. This

section discusses how Free Software comes into existence. But first, it

addresses how software can be non-Free in the first place.

Software can be made proprietary only because it is governed by copyright

law.\footnote{This statement is a bit of an oversimplification. Patents

  and trade secrets can cover software and make it effectively non-Free,

  one can contract away their rights and freedoms regarding software, or

  source code can be practically obscured in binary-only distribution

  without reliance on any legal system. However, the primary control

  mechanism for software is copyright.} Copyright law, with respect to

software, governs copying, modifying, and redistributing that

software.\footnote{Copyright law in general also governs ``public

  performance'' of copyrighted works. There is no generally agreed

  definition for public performance of software and both GPLv2 and GPLv3

  do not govern public performance.} By law, the copyright holder (a.k.a.

the author) of the work controls how others may copy, modify and/or

distribute the work. For proprietary software, these controls are used to

prohibit these activities. In addition, proprietary software distributors

further impede modification in a practical sense by distributing only

binary code and keeping the source code of the software secret.

Copyright law is a construction. In the USA, the Constitution permits,

but does not require, the creation of copyright law as federal

legislation. Software, since it is an idea fixed in a tangible medium, is

thus covered by the statues, and is copyrighted by default.

However, this legal construction is not necessarily natural. Software, in

its natural state without copyright, is Free Software. In an imaginary

world with no copyright, the rules would be different. In this

world, when you received a copy of a program's source code, there would be

no default legal system to restrict you from sharing it with others,

making modifications, or redistributing those modified

versions.\footnote{There could still exist legal systems, like our modern

  patent system, which could restrict the software in other ways.}

Software in the real world is copyrighted by default and is

automatically covered by that legal system. However, it is possible

to move software out of the domain of the copyright system. A

copyright holder is always permitted to \defn{disclaim} their

copyright. If copyright is disclaimed, the software is not governed

by copyright law. Software not governed by copyright is in the

``public domain.''

\subsection{Public Domain Software}

% FIXME: this section needs more improvements to make it clear that public

% domain dedication is difficult, if not impossible.

% Karen suggests that talking about USA government software being public

% domain might make sense here.

Theoretically, an author can create public domain software by disclaiming all

copyright interest on the work. In the USA and other countries that have

signed the Berne convention on copyright, software is copyrighted

automatically by the author when she ``fixes the software into a tangible

medium.''  In the software world, this usually means typing the source code

of the software into a file.

Imagine if an author can truly disclaim that default control given to her by the

copyright laws. Once this is done, the software is in the public domain

--- it is no longer covered by copyright. Since it is copyright law that

allows for various controls on software (i.e., prohibition of copying,

modification, and redistribution), removing the software from the

copyright system and placing it into the public domain does yield Free

Software.

Carefully note that software in the public domain is \emph{not} licensed

in any way. It is nonsensical to say software is ``licensed for the

public domain,'' or any phrase that implies the copyright holder gave

expressed permission to take actions governed by copyright law.

By contrast, what the copyright holder has done is renounce her copyright

controls on the work. The law gave her controls over the work, and she

has chosen to waive those controls. Software in the public domain is

absent copyright and absent a license. The software freedoms discussed in

Section~\ref{Free Software Definition} are all granted because there is no

legal system in play to take them away.

\subsection{Why Copyright Free Software?}

If simply disclaiming copyright on software yields Free Software, then it

stands to reason that putting software into the public domain is the

easiest and most straightforward way to produce Free Software. Indeed,

some major Free Software projects have chosen this method for making their

software Free. However, most of the Free Software in existence \emph{is}

copyrighted. In most cases (particularly in those of FSF and the GNU

Project), this was done due to very careful planning.

Software released into the public domain does grant freedom to those users

who receive the standard versions on which the original author disclaimed

copyright. However, since the work is not copyrighted, any nontrivial

modification made to the work is fully copyrightable.

Free Software released into the public domain initially is Free, and

perhaps some who modify the software choose to place their work into the

public domain as well. However, over time, some entities will choose to

proprietarize their modified versions. The public domain body of software

feeds the proprietary software. The public commons disappears, because

fewer and fewer entities have an incentive to contribute back to the

commons. They know that any of their competitors can proprietarize their

enhancements. Over time, almost no interesting work is left in the public

domain, because nearly all new work is done by proprietarization.

A legal mechanism is needed to redress this problem. FSF was in fact

originally created primarily as a legal entity to defend software freedom,

and that work of defending software freedom is a substantial part of

its work today. Specifically because of this ``embrace, proprietarize and

extend'' cycle, FSF made a conscious choice to copyright its Free Software,

and then license it under ``copyleft'' terms. Many, including the

developers of the kernel named Linux, have chosen to follow this paradigm.

Copyleft is a legal strategy to defend, uphold and propagate software

freedom. The basic technique of copyleft is as follows: copyright the

software, license it under terms that give all the software freedoms, but

use the copyright law controls to ensure that all who receive a copy of

the software have equal rights and freedom. In essence, copyleft grants

freedom, but forbids others to forbid that freedom to anyone else along

the distribution and modification chains.

Copyleft is a general concept. Much like ideas for what a computer might

do must be \emph{implemented} by a program that actually does the job, so

too must copyleft be implemented in some concrete legal structure.

``Share and share alike'' is a phrase that is used often enough to explain the

concept behind copyleft, but to actually make it work in the real world, a

true implementation in legal text must exist. The GPL is the primary

implementation of copyleft in copyright licensing language.

\section{A Community of Equality}

The GPL uses copyright law to defend freedom and equally ensure users'

rights. This ultimately creates an community of equality for both

business and noncommercial users.

\subsection{The Noncommercial Community}

A GPL'd code base becomes a center of a vibrant development and user

community. Traditionally, volunteers, operating noncommercially out of

keen interest or ``scratch an itch'' motivations, produce initial versions

of a GPL'd system. Because of the efficient distribution channels of the

Internet, any useful GPL'd system is adopted quickly by noncommercial

users.

Fundamentally, the early release and quick distribution of the software

gives birth to a thriving noncommercial community. Users and developers

begin sharing bug reports and bug fixes across a shared intellectual

commons. Users can trust the developers, because they know that if the

developers fail to address their needs or abandon the project, the GPL

ensures that someone else has the right to pick up development.

Developers know that the users cannot redistribute their software without

passing along the rights granted by GPL, so they are assured that every

one of their users is treated equally.

Because of the symmetry and fairness inherent in GPL'd distribution,

nearly every GPL'd package in existence has a vibrant noncommercial user

and developer base.

\subsection{The Commercial Community}

By the same token, nearly all established GPL'd software systems have a

vibrant commercial community. Nearly every GPL'd system that has gained

wide adoption from noncommercial users and developers eventually begins

to fuel a commercial system around that software.

For example, consider the Samba file server system that allows Unix-like

systems (including GNU/Linux) to serve files to Microsoft Windows systems.

Two graduate students originally developed Samba in their spare time and

it was deployed noncommercially in academic environments. However, very

soon for-profit companies discovered that the software could work for them

as well, and their system administrators began to use it in place of

Microsoft Windows NT file-servers. This served to lower the cost of

running such servers by orders of magnitude. There was suddenly room in

Windows file-server budgets to hire contractors to improve Samba. Some of

the first people hired to do such work were those same two graduate

students who originally developed the software.

The noncommercial users, however, were not concerned when these two

fellows began collecting paychecks off of their GPL'd work. They knew

that because of the nature of the GPL that improvements that were

distributed in the commercial environment could easily be folded back into

the standard version. Companies are not permitted to proprietarize

Samba, so the noncommercial users, and even other commercial users are

safe in the knowledge that the software freedom ensured by GPL will remain

protected.

Commercial developers also work in concert with noncommercial

developers. Those two now-long-since graduated students continue to