GPLv3\S~5, it is clear that if one conveys \textit{only} source code, one can

never be required to provide more than that.  One always has the right to

modify a source code work by deleting any part of it, and there can be no

requirement that free software source code be a whole functioning program.

\subsection{The System Library Exception}

The previous section skipped over one part of the CCS definition, the

so-called system library exception.  The ``System Libraries'' definition (and

the ``Standard Interface'' and ``Major Component'' definitions, which it

includes) are designed as part

to permit certain distribution arrangements that are considered reasonable by

copyleft advocates.  The system library exception is designed to allow

copylefted software to link with these libraries when such linking would hurt

software freedom more than it would hurt proprietary software.

The system library exception has two parts.  Part (a) rewords the GPLv2

exception for clarity replaces GPLv2's words ``unless that component itself

accompanies the executable'' with ``which is not part of the Major

Component''.  The goal here is to not require disclosure of source code of

certain libraries, such as necessary Microsoft Windows DLLs (which aren't

part of Windows' kernel but accompany it) that are required for functioning

of copylefted programs compiled for Windows.

However, in isolation, (a) would be too permissive, as it would sometimes

allowing distributors to evade important GPL requirements.  Part (b) reigns

in (a).  Specifically, (b) specifies only a few functionalities that a the

system library may provide and still qualify for the exception.  The goal is

to ensure system libraries are truly adjunct to a major essential operating

system component, compiler, or interpreter.  The more low-level the

functionality provided by the library, the more likely it is to be qualified

for this exception.

Admittedly, the system library exception is a frequently discussed topic of

obsessed GPL theorists.  The amount that has been written on the system

library exception (both the GPLv2 and GPLv3 versions of it), if included

herein,  could easily increase this section of the tutorial to a length

greater than all the others.

Like any exception to the copyleft requirements of GPL, would-be GPL

violators frequently look to the system library exception as a potential

software freedom circumvention technique.  When considering whether or not a

library qualifies for the system library exception, here is a pragmatic

thesis to consider, based on the combined decades of experience in GPL

interpretation of this tutorial's authors: the harder and more strained the

reader must study and read the system library exception, the more likely it

is that the library in question does not qualify for it.

\section{GPLv3~\S2: Basic Permissions}

GPLv3~\S2 can roughly be considered as an equivalent to GPLv2~\S0 (discussed

in \S~\ref{GPLv2s0} of this tutorial).  However, the usual style of

improvements found in GPLv3 are found here as well.  For example, the first

sentence of GPLv3~\S2 furthers the goal internationalization.  Under the

copyright laws of some countries, it may be necessary for a copyright license

to include an explicit provision setting forth the duration of the rights

being granted. In other countries, including the USA, such a provision is

unnecessary but permissible.

GPLv3~\S2\P1 also acknowledges that licensees under the GPL enjoy rights of

copyright fair use, or the equivalent under applicable law.  These rights are

compatible with, and not in conflict with, the freedoms that the GPL seeks to

protect, and the GPL cannot and should not restrict them.

However, note that (sadly to some copyleft advocates) the unlimited freedom

to run is confined to the \textit{unmodified} Program.  This confinement is

unfortunately necessary since Programs that do not qualify as a User Product

in GPLv3~\S6 (see \S~\ref{user-product} in this tutorial) might have certain

unfortunate restrictions on the freedom to run\footnote{See

  \S~ref{freedom-to-run} of this tutorial for the details on ``the freedom to

  run''.}

GPLv3~\S2\P2 distinguishes between activities of a licensee that are

permitted without limitation and activities that trigger additional

requirements.  Specifically, GPLv3~\S2\P2 guarantees the basic freedoms of

privately modifying and running the program.

Also, GPLv3~\S2\P2 gives an explicit permission for a client to provide a

copy of its modified software to a contractor exclusively for that contractor

to modify it further, or run it, on behalf of the client.  However, the

client can \textit{only} exercise this control over its own copyrighted

changes to the GPL-covered program.  The parts of the program it obtained

from other contributors must be provided to the contractor with the usual GPL

freedoms.  Thus, GPLv3 permits users to convey covered works to contractors

operating exclusively on the users' behalf, under the users' direction and

control, and to require the contractors to keep the users' copyrighted

changes confidential, but \textit{only if} the contractor is limited to acting

on the users' behalf (just as the users' employees would have to act).

The strict conditions in this ``contractors provision'' are needed so that it

cannot be twisted to fit other activities, such as making a program available

to downstream users or customers.  By making the limits on this provision

very narrow, GPLv3 ensures that, in all other cases, contractors gets the

full freedoms of the GPL that they deserve.

GPLv3~\S2's final paragraph includes an explicit prohibition of sublicensing.

This provision ensures that GPL enforcement is always by the copyright

holder.  Usually, sublicensing is regarded as a practical convenience or

necessity for the licensee, to avoid having to negotiate a license with each

licensor in a chain of distribution.  The GPL solves this problem in another

way --- through its automatic licensing provision found in GPLv3\~S10 (which

is discussed in more detail in \S\~ref{GPLv3s10} of this tutorial).

\section{GPLv3's views on DRM and Device Lock-Down}

\label{GPLv3-drm}

The issues of DRM, device lock-down and encryption key disclosure were the

most hotly debated during the GPLv3 process.  FSF's views on this were sadly

frequently misunderstood and, comparing the provisions related to these

issues in the earliest drafts of GPLv3 to  the final version of GPLv3 shows

the FSF's willingness to compromise on tactical issues to reach the larger

goal of software freedom.

Specifically, GPLv3 introduced provisions that respond to the growing

practice of distributing GPL-covered programs in devices that employ

technical means to restrict users from installing and running modified

versions.  This practice thwarts the expectations of developers and users

alike, because the right to modify is one of the core freedoms the GPL is

designed to secure.

Technological measures to defeat users' rights.  These measures are often

described by such Orwellian phrases, such as ``digital rights management,''

which actually means limitation or outright destruction of users' legal

rights, or ``trusted computing,'' which actually means selling people

computers they cannot trust.  However, these measures are alike in one basic

respect.  They all employ technical means to turn the system of copyright law

(where the powers of the copyright holder are limited exceptions to general

freedom) into a virtual prison, where everything not specifically permitted

is utterly forbidden.  This system of ``para-copyright'' was created well

after GPLv2 was written --- initially through legislation in the USA and the

EU, and later in other jurisdictions as well.  This legislation creates

serious civil or even criminal penalties to escape from these restrictions

(commonly and aptly called ``jail-breaking a device''), even where the

purpose in doing so is to restore the users' legal rights that the technology

wrongfully prevents them from exercising.

GPLv2 did not address the use of technical measures to take back the rights

that the GPL granted, because such measures did not exist in 1991, and would

have been irrelevant to the forms in which software was then delivered to

users.  GPLv3 addresses these issues, particularly because copylefted

software is ever more widely embedded in devices that impose technical

limitations on the user's freedom to change it.

However, FSF always made a clear distinction to avoid conflating these

``lock-down'' measures with legitimate applications that give users control,

as by enabling them to choose higher levels of system or data security within

their networks, or by allowing them to protect the security of their

communications using keys they can generate or copy to other devices for

sending or receiving messages.  Such technologies present no obstacles to

software freedom and the goals of copyleft.

The public GPLv3 drafting process sought to balance these positions of

copyleft advocates with various desperate views of the larger

Free-Software-using community.  Ultimately, FSF compromised to the GPLv3\S3

and GPLv3\S6 provisions that, taken together, are a minimalist set of terms

sufficient to protect the software freedom against the threat of invasive

para-copyright.

The compromises made were ultimately quite reasonable.  The primary one is

embodied in GPLv3\S6's ``User Product'' definition (see \S~\ref{user-product}

in this tutorial for details).  Additionally, some readers of early GPLv3

drafts seem to have assumed GPLv3 contained a blanket prohibition on DRM; but

it does not.  In fact, no part of GPLv3 forbids DRM regarding non-GPL'd

works; rather, GPLv3 forbids the use of DRM specifically to lock-down

restrictions on users' ability to install modified versions of the GPL'd

software itself, but again, \textit{only} with regard to User Products.

\section{GPLv3~\S3: What Hath DMCA Wrought}

\label{GPLv3s3}

As discussed in \S~\ref{software-and-non-copyright} of this tutorial,

\href{http://www.law.cornell.edu/uscode/text/17/1201}{17 USC~\S1201} and

relate sections\footnote{These sections of the USC are often referred to as

  the ``Digital Millennium Copyright Act'', or ``DMCA'', as that was the name

  of the bill that so-modified these sections of the USC\@.} prohibits users

from circumventing technological measures that implement DRM\@.  Since this

is part of copyright law and the GPL is primarily a copyright license, and

since what the DMCA calls ``circumvention'' is simply ``modifying the

software'' under the GPL, GPLv3 must disclaim such anti-circumvention

provisions are not applicable to the GPLv3'd software.  GPLv3\S3 shields

users from being subjected to liability under anti-circumvention law for

exercising their rights under the GPL, so far as the GPL can do so.

First, GPLv3\S3\P1 declares that no GPL'd program is part of an effective

technological protection measure, regardless of what the program does.  Early

drafts of GPLv3\S3\P1 referred directly to the DMCA, but the final version

instead includes instead an international legal reference to

anticircumvention laws enacted pursuant to the 1996 WIPO treaty and any

similar laws.  Lawyers outside the USA worried that a USA statutory reference

could be read as indicating a choice for application of USA law to the