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 previous section set forth key freedoms and rights that are referred to

as ``software freedom''.  This section discusses the licensing mechanisms

used to enable software freedom.  These licensing mechanism were ultimately

created as a community-oriented ``answer'' to the existing proprietary

software licensing mechanisms.  Thus, first, consider carefully why

proprietary software exists in the first place.

Proprietary software exists at all only because it is governed by copyright

law.\footnote{This statement is admittedly an oversimplification. Patents and

  trade secrets can cover software and make it effectively non-Free, and 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, and therefore this section focuses on how copyright

  restrictions make software proprietary.} Copyright law, with respect to

software, typically governs copying, modifying, and redistributing that

software (For details of this in the USA, see

\href{http://www.copyright.gov/title17/92chap1.html#106}{\S 106} and

\href{http://www.copyright.gov/title17/92chap1.html#117}{\S 117} of

\href{http://www.law.cornell.edu/uscode/text/17}{Title 17} of the

\textit{United States Code}).\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 (in the USA and in most other

jurisdictions), the copyright holder (most typically, 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 is not a natural state, it is a legal construction. In the USA, the

Constitution permits, but does not require, the creation of copyright law as

federal legislation.  Software, since it is ``an original works of authorship

fixed in any tangible medium of expression ...  from which they can be

perceived, reproduced, or otherwise communicated, either directly or with the

aid of a machine or device'' (as stated in

\href{http://www.law.cornell.edu/uscode/text/17/102}{17 USC \S 102}), is thus

covered by the statues, and is copyrighted by default.

However, 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{Note that this is again an oversimplification; the

  complexities with this argument are discussed in

  Section~\ref{software-and-non-copyright}.}

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 can often

\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}

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 authors could truly disclaim those default control of copyright

law.  If so, the software is in the public domain -- no longer covered by

copyright.  Since copyright law is the construction allowing for most

restrictions on software (i.e., prohibition of copying, modification, and

redistribution), removing the software from the copyright system usually

yields software freedom for its users.

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, the copyright holders instead renounced copyright controls on

the work.  The law gave the copyright holder exclusive controls over the

work, and they chose 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.

Admittedly, a discussion of public domain software is an oversimplified

example.  First, disclaimer of copyright is actually difficult in practice.

Because copyright controls are usually automatically granted and because, in

some jurisdictions, some copyright controls cannot be waived (See

Section~\ref{non-usa-copyright} for further discussion), many copyright

holders sometimes incorrectly believe a work has been placed in the public

domain.  Second, due to aggressive lobbying by the entertainment industry,

the ``exclusive Right'' of copyright, that was supposed to only exist for

``Limited Times'' according to the USA Constitution, appears to be infinite:

simply purchased on the installment plan rather than in whole.  Thus, we must

assume no works of software will fall into the public domain merely due to

the passage of time.

The best example of software known to be in the public domain is software

that is published exclusively produced by the USA government.  Under

\href{http://www.law.cornell.edu/uscode/text/17/105}{17 USC 101 \S 105}, all

works published by the USA Government are not copyrightable.

\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.

\subsection{Software and Non-Copyright Legal Regimes}

\label{software-and-non-copyright}

The use, modification and distribution of software, like many endeavors,

simultaneously interacts with multiple different legal regimes.  As was noted

early via footnotes, copyright is merely the \textit{most common way} to

restrict users' rights to copy, share, modify and/or redistribute software.

However, proprietary software licenses typically use every mechanism

available to subjugate users.  For example:

\begin{itemize}

\item Unfortunately, despite much effort by many in the software freedom

  community to end patents that read on software (i.e., patents on

  computational ideas), they still ultimately exist.  As such, a software

  program might otherwise be seemly unrestricted, but a patent might read on

  the software and ruin everything for its users.\footnote{See

  \S\S~\ref{gpl-implied-patent-grant},~\ref{GPLs7},~\ref{GPLv3s11} for more

  discussion on how the patent system interacts with copyleft, and read

  Richard M.~Stallman's essay,

  \href{http://www.wired.com/opinion/2012/11/richard-stallman-software-patents/}{\textit{Let’s

      Limit the Effect of Software Patents, Since We Can’t Eliminate Them}}

  for more information on the problems these patents present to society.}

\item Digital Restrictions Management (usually called \defn{DRM}) is often

  used to impose technological restrictions on users' ability to exercise

  software freedom that they might otherwise be granted\footnote{See

    \S~\ref{GPLv3s3} for more information on how GPL deals with this issue.}.

  The simplest (and perhaps oldest) form of DRM, of course, is separating

  software source code (read by humans), from their compiled binaries (read

  only by computers).  Furthermore,

  \href{http://www.law.cornell.edu/uscode/text/17/1201}{17 USC 1201} often

  prohibits users legally from circumventing some of these DRM systems.

\subsection{Non-USA Copyright Regimes}

\label{non-usa-copyright}

Generally speaking, copyright law operates similarly enough in countries that

have signed the Berne Convention on Copyright, and software freedom licenses

have generally taken advantage of this international standardization of

copyright law.  However, copyright law does differ from country to country,

and commonly, software freedom licenses like GPL must be considered under the

copyright law in the jurisdiction where any licensing dispute occurs.

Those who are most familiar with the USA's system of copyright often are

surprised to learn that there are certain copyright controls that cannot be

waived nor disclaimed.

FIXME: moral rights.

\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

contribute to Samba altruistically, but also get paid work doing it.

Priorities change when a client is in the mix, but all the code is

contributed back to the standard version. Meanwhile, many other

individuals have gotten involved noncommercially as developers,

because they want to ``cut their teeth on Free Software,'' or because

the problems interest them. When they get good at it, perhaps they

will move on to another project, or perhaps they will become

commercial developers of the software themselves.

No party is a threat to another in the GPL software scenario because

everyone is on equal ground. The GPL protects rights of the commercial

and noncommercial contributors and users equally. The GPL creates trust,

because it is a level playing field for all.

\subsection{Law Analogy}

In his introduction to Stallman's \emph{Free Software, Free Society},

Lawrence Lessig draws an interesting analogy between the law and Free

Software. He argues that the laws of a free society must be protected

much like the GPL protects software. So that I might do true justice to

Lessig's argument, I quote it verbatim:

\begin{quotation}

A ``free society'' is regulated by law. But there are limits that any free

society places on this regulation through law: No society that kept its

laws secret could ever be called free. No government that hid its

regulations from the regulated could ever stand in our tradition. Law

controls. But it does so justly only when visibly. And law is visible

only when its terms are knowable and controllable by those it regulates,

or by the agents of those it regulates (lawyers, legislatures).

This condition on law extends beyond the work of a legislature. Think

about the practice of law in American courts. Lawyers are hired by their

clients to advance their clients' interests. Sometimes that interest is

advanced through litigation. In the course of this litigation, lawyers

write briefs. These briefs in turn affect opinions written by judges.

These opinions decide who wins a particular case, or whether a certain law

can stand consistently with a constitution.

All the material in this process is free in the sense that Stallman means.

Legal briefs are open and free for others to use. The arguments are

transparent (which is different from saying they are good), and the

reasoning can be taken without the permission of the original lawyers.

The opinions they produce can be quoted in later briefs. They can be

copied and integrated into another brief or opinion. The ``source code''

for American law is by design, and by principle, open and free for anyone

to take. And take lawyers do---for it is a measure of a great brief that

it achieves its creativity through the reuse of what happened before. The

source is free; creativity and an economy is built upon it.

This economy of free code (and here I mean free legal code) doesn't starve

lawyers. Law firms have enough incentive to produce great briefs even

though the stuff they build can be taken and copied by anyone else. The

lawyer is a craftsman; his or her product is public. Yet the crafting is

not charity. Lawyers get paid; the public doesn't demand such work

without price. Instead this economy flourishes, with later work added to

the earlier.

We could imagine a legal practice that was different---briefs and

arguments that were kept secret; rulings that announced a result but not

the reasoning. Laws that were kept by the police but published to no one

else. Regulation that operated without explaining its rule.

We could imagine this society, but we could not imagine calling it

``free.''  Whether or not the incentives in such a society would be better

or more efficiently allocated, such a society could not be known as free.

The ideals of freedom, of life within a free society, demand more than

efficient application. Instead, openness and transparency are the

constraints within which a legal system gets built, not options to be

added if convenient to the leaders. Life governed by software code should

be no less.

Code writing is not litigation. It is better, richer, more

productive. But the law is an obvious instance of how creativity and

incentives do not depend upon perfect control over the products

created. Like jazz, or novels, or architecture, the law gets built

upon the work that went before. This adding and changing is what

creativity always is. And a free society is one that assures that its

most important resources remain free in just this sense.\footnote{This

quotation is Copyright \copyright{} 2002, Lawrence Lessig. It is

licensed under the terms of

\texttt{http://creativecommons.org/licenses/by/1.0/}{the ``Attribution

License'' version 1.0} or any later version as published by Creative

Commons.}

\end{quotation}

In essence, lawyers are paid to service the shared commons of legal

infrastructure. Few citizens defend themselves in court or write their

own briefs (even though they are legally permitted to do so) because

everyone would prefer to have an expert do that job.

The Free Software economy is a market ripe for experts. It

functions similarly to other well established professional fields like the

law. The GPL, in turn, serves as the legal scaffolding that permits the

creation of this vibrant commercial and noncommercial Free Software

economy.

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

\chapter{A Tale of Two Copyleft Licenses}

\section{Historical Motivations for the General Public License}

\section{Proto-GPLs And Their Impact}

\section{The GNU General Public License, Version 1}

\section{The GNU General Public License, Version 2}

\section{The GNU General Public License, Version 3}

\section{The Innovation of Optional ``Or Any Later'' Version}

\section{Complexities of Two Simultaneously Popular Copylefts}

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