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

\href{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}

While determining the proper methodology and criteria to yield an accurate

count remains difficult, the GPL is generally considered one of the most

widely used Free Software licenses.  For most of its history --- for 16 years

from June 1991 to June 2007 --- there was really only one version of the GPL,

version 2.

However, the GPL had both earlier versions before version 2, and, more well

known, a revision to version 3. 

\section{Historical Motivations for the General Public License}

The earliest license to grant software freedom was likely the Berkeley

Software Distribution (``BSD'') license.  This license is typical of what are

often called lax, highly permissive licenses.  Not unlike software in the

public domain, these non-copyleft licenses (usually) grant software freedom

to users, but they do not go to any effort to uphold that software freedom

for users.  The so-called ``downstream'' (those who receive the software and

then build new things based on that software) can restrict the software and

distribute further.

The GNU's Not Unix (``GNU'') project, which Richard M.~Stallman (``RMS'')

founded in 1984 to make a complete Unix-compatible operating system

implementation that assured software freedom for all.  However, RMS saw that

using a license that gave but did not assure software freedom would be

counter to the goals of the GNU project.  RMS invented ``copyleft'' as an

answer to that problem, and began using various copyleft licenses for the

early GNU project programs\footnote{RMS writes more fully about this topic in

  his essay entitled simply

  \href{http://www.gnu.org/gnu/thegnuproject.html}{\textit{The GNU Project}.

    For those who want to hear the story in his own voice,

    \href{http://audio-video.gnu.org/audio/}{speech recordings} of his talk,

    \textit{The Free Software Movement and the GNU/Linux Operating System}

    are also widely available}.

\section{Proto-GPLs And Their Impact}

The earliest copyleft licenses were specific to various GNU programs.  For

example, \href{http://www.free-soft.org/gpl_history/emacs_gpl.html}{The Emacs

  General Public License} was likely the first copyleft license ever

published.  Interesting to note that even this earliest copyleft license

contains a version of the well-known GPL copyleft clause:

\begin{quotation}

You may modify your copy or copies of GNU Emacs \ldots provided that you also

\ldots cause the whole of any work that you distribute or publish, that in

whole or in part contains or is a derivative of GNU Emacs or any part

thereof, to be licensed at no charge to all third parties on terms identical

to those contained in this License Agreement.

\end{quotation}

This simply stated clause is the fundamental innovation of copyleft.

Specifically, copyleft \textit{uses} the copyright holders' controls on

permission to modify the work to add a conditional requirement.  Namely,

downstream users may only have permission to modify  the work if they pass

along the same permissions on the modified version that came originally to

them.

These original program-specific proto-GPLs give an interesting window into

the central ideas and development of copyleft.  In particular, reviewing them

shows how the text of the GPL we know has evolved to address more of the

issues discussed earlier in \S~\ref{software-and-non-copyright}.

\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}

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

\chapter{GPLv2: Running Software and Verbatim Copying}

\label{run-and-verbatim}

This chapter begins the deep discussion of the details of the terms of

GPLv2\@. In this chapter, we consider the first two sections: GPLv2 \S\S

0--2. These are the straightforward sections of the GPL that define the

simplest rights that the user receives.

\section{GPLv2 \S 0: Freedom to Run}

\label{GPLs0}

\S 0, the opening section of GPLv2, sets forth that the work is governed by

copyright law. It specifically points out that it is the ``copyright

holder'' who decides if a work is licensed under its terms and explains

how the copyright holder might indicate this fact.

A bit more subtly, \S 0 makes an inference that copyright law is the only

system under which it is governed. Specifically, it states:

\begin{quote}

Activities other than copying, distribution and modification are not

covered by this License; they are outside its scope.

\end{quote}

In essence, the license governs \emph{only} those activities, and all other

activities are unrestricted, provided that no other agreements trump GPLv2

(which they cannot; see Sections~\ref{GPLs6} and~\ref{GPLs7}). This is

very important, because the Free Software community heavily supports

users' rights to ``fair use'' and ``unregulated use'' of copyrighted

material. GPLv2 asserts through this clause that it supports users' rights

to fair and unregulated uses.

Fair use of copyrighted material is an established legal doctrine that

permits certain activities. Discussion of the various types of fair

use activity are beyond the scope of this tutorial. However, one

important example of fair use is the right to quote a very few lines

(less than seven or so) and reuse them as you would with or without

licensing restrictions.

Fair use is a doctrine established by the courts or by statute. By

contrast, unregulated uses are those that are not covered by the statue

nor determined by a court to be covered, but are common and enjoyed by

many users. An example of unregulated use is reading a printout of the

program's source code like an instruction book for the purpose of learning

how to be a better programmer.

\medskip

Thus, the GPLv2 protects users fair and unregulated use rights precisely by

not attempting to cover them. Furthermore, the GPLv2 ensures the freedom

to run specifically by stating the following:

\begin{quote}

''The act of running the Program is not restricted.''

\end{quote}

Thus, users are explicitly given the freedom to run by \S 0.

\medskip

The bulk of \S 0 not yet discussed gives definitions for other terms used

throughout. The only one worth discussing in detail is ``work based on

the Program.''  The reason this definition is particularly interesting is

not for the definition itself, which is rather straightforward, but

because it clears up a common misconception about the GPL\@.

The GPL is often mistakenly criticized because it fails to give a

definition of ``derivative work.''  In fact, it would be incorrect and

problematic if the GPL attempted to define this. A copyright license, in

fact, has no control over what may or may not be a derivative work. This

matter is left up to copyright law, not the licenses that utilize it.

It is certainly true that copyright law as a whole does not propose clear

and straightforward guidelines for what is and is not a derivative

software work under copyright law. However, no copyright license --- not

even the GNU GPL --- can be blamed for this. Legislators and court

opinions must give us guidance to decide the border cases.

\section{GPLv2 \S 1: Verbatim Copying}

\label{GPLs1}

GPLv2 \S 1 covers the matter of redistributing the source code of a program

exactly as it was received. This section is quite straightforward.

However, there are a few details worth noting here.

The phrase ``in any medium'' is important. This, for example, gives the

freedom to publish a book that is the printed copy of the program's source

code. It also allows for changes in the medium of distribution. Some

vendors may ship Free Software on a CD, but others may place it right on

the hard drive of a pre-installed computer. Any such redistribution media