non-copyleft permissive licenses include such clauses.

\item This provision allows indemnification requirements of authors and

  licensors.  The FSF specifically designed this clause to achieve GPLv3

  compatibility for the

  \href{http://www.apache.org/licenses/LICENSE-2.0.html}{Apache Software

    License, Version 2.0}.

\end{enumerate}

During the GPLv3 drafting process, some questioned the necessity of GPLv3~\S7;

those critics suggested that it creates complexity that did not previously

exist.  However, by the time of GPLv3's drafting, many existing GPLv2'd

software packages already combined with various non-copylefted Free Software

licensed code that carried such additional terms.  Therefore, GPLv3~\S7 is

rationalized existing practices of those package authors and modifiers, since

it sets clear guidelines regarding the removal and addition of these

additional terms.  With its carefully limited list of allowed additional

requirements, GPLv3\S7 accomplishes additional objectives as well, since it

permits the expansion of the base of code available for GPL developers, while

also encouraging useful experimentation with requirements the GPLv3 does not

include by default.

However, any other non-permissive additional terms apart from those stated

above are considered ``further'' restrictions which

\hyperref[GPLv3s10]{GPLv3~\S10} prohibits.  Furthermore, as a compliance

matter, if you add additional terms in accordance with GPLv3~\S7, you must

ensure that the terms are placed in the relevant source files or provide a

conspicuous notice about where to find the additional terms.

\section{GPLv3~\S8: A Lighter Termination}

GPLv2 provided for automatic termination of the rights of a person who

copied, modified, sublicensed, or distributed a work in violation of the

license.  Automatic termination can be too harsh for those who have committed

an inadvertent violation, particularly in cases involving distribution of

large collections of software having numerous copyright holders.  A violator

who resumes compliance with GPLv2 technically needs to obtain forgiveness

from all copyright holders, and even contacting them all might be impossible.

GPLv3~\S8 now grants opportunities for provisional and permanent

reinstatement of rights. The termination procedure provides a limited

opportunity to cure license violations.  If a licensee has committed a

first-time violation of the GPL with respect to a given copyright holder, but

the licensee cures the violation within 30 days following receipt of notice

of the violation, then any of the licensee's GPL rights that have been

terminated by the copyright holder are ``automatically reinstated''.

Finally, if a licensee violates the GPL, a contributor may terminate any

patent licenses that it granted under GPLv3~\S11, in addition to any

copyright permissions the contributor granted to the licensee.

% FIXME-LATER: write more here, perhaps linking up to enforcement

\section{GPLv3~\S9: Acceptance}

GPLv3~\S9 means what it says: mere receipt or execution of code neither

requires nor signifies contractual acceptance under the GPL.  Speaking more

broadly, GPLv3 is intentionally structured as a unilateral grant

of copyright permissions, the basic operation of which exists outside of any

law of contract.  Whether and when a contractual relationship is formed

between licensor and licensee under local law do not necessarily matter to

the working of the license.

\section{GPLv3~\S10: Explicit Downstream License}

\label{GPLv3s10}

GPLv3~\S10 is a generally straightforward section that ensures that everyone

downstream receives licenses from all copyright holders.  Each time you

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

under the terms of GPL, from every upstream licensor whose copyrighted

material is present in the work you redistribute.  You could think of this as

creating a three-dimensional rather than linear flow of license rights.

Every recipient of the work is ``in privity,'' or is directly receiving a

license from every licensor.

This mechanism of automatic downstream licensing is central to copyleft's

function.  Every licensor independently grants licenses, and every licensor

independently terminates the license on violation.  Parties further

downstream from the infringing party remain licensed, so long as they don't

themselves commit infringing actions.  Their licenses come directly from all

the upstream copyright holders, and are not dependent on the license of the breaching

party who distributed to them.  For the same reason, an infringer who acquires

another copy of the program has not thereby acquired any new license rights:

once any upstream licensor of that program has terminated the license for

breach of its terms, no new automatic license will issue to the recipient

just by acquiring another

copy\footnote{Footnote~\ref{German-reinstatement-footnote} also applies here

  in discussion of GPLv3 just as it did in discussion of GPLv2.}

Meanwhile, one specific addition in GPLv3 here in GPLv3~\S10 deserves special

mention.  Specifically, GPLv3 removed the words ``at no charge'' from

GPLv2~\S2(b) (which, BTW, became GPLv3~\S5(b)) because it contributed to a misconception that the GPL did not

permit charging for distribution of copies.  The purpose of the ``at no

charge'' wording was to prevent attempts to collect royalties from third

parties.  The removal of these words created the danger that the imposition

of licensing fees would no longer be seen as a license violation.  Therefore,

GPLv3~\S10 adds a new explicit prohibition on imposition of licensing fees or

royalties.  This section is an appropriate place for such a clause, since it

is a specific consequence of the general requirement that no further

restrictions be imposed on downstream recipients of GPL-covered code.

% FIXME-LATER: This text needs further study before I can conclude it belongs

% in this tutorial:

%% Careful readers of the GPL have suggested that its explicit prohibition

%% against imposition of further restrictions\footnote{GPLv2, section 6; Draft

%%   3, section 10, third paragraph.} has, or ought to have, implications for

%% those who assert patents against other licensees.  Draft 2 took some steps to

%% clarify this point in a manner not specific to patents, by describing the

%% imposition of ``a license fee, royalty, or other charge'' for exercising GPL

%% rights as one example of an impermissible further restriction.  In Draft 3 we

%% have clarified further that the requirement of non-imposition of further

%% restrictions has specific consequences for litigation accusing GPL-covered

%% programs of infringement.  Section 10 now states that ``you may not initiate

%% litigation (including a cross-claim or counterclaim in a lawsuit) alleging

%% that any patent claim is infringed by making, using, selling, offering for

%% sale, or importing the Program (or the contribution of any contributor).''

%% That is to say, a patent holder's licensed permissions to use a work under

%% GPLv3 may be terminated under section 8 if the patent holder files a lawsuit

%% alleging that use of the work, or of any upstream GPLv3-licensed work on

%% which the work is based, infringes a patent.

\section{GPLv3~\S11: Explicit Patent Licensing}

\label{GPLv3s11}

Software patenting is a harmful and unjust policy, and should be abolished;

recent experience makes this all the more evident. Since many countries grant

patents that can apply to and prohibit software packages, in various guises

and to varying degrees, GPLv3 seeks to protect the users of GPL-covered programs

from those patents, while at the same time making it feasible for patent

holders to contribute to and distribute GPL-covered programs as long as they

do not attack the users of those programs.

It is generally understood that GPLv2 implies some limits on a licensee's

power to assert patent claims against the use of GPL-covered works.

However, the patent licensing practice that GPLv2~\S7 (corresponding to

GPLv3~\S12) is designed to prevent is only one of several ways in which

software patents threaten to make free programs non-free and to prevent users

from exercising their rights under the GPL. GPLv3 takes a more comprehensive

approach to combating the danger of patents.

GPLv2~\S7 has seen some success in deterring conduct that would otherwise

result in denial of full downstream enjoyment of GPL rights, and thus it is

preserved in GPLv3~\S12.  Experience has shown that more is necessary,

however, to ensure adequate community safety where companies act in concert

to heighten the anticompetitive use of patents that they hold or license.

Therefore,  GPLv3 is designed to reduce the patent risks that distort and

threaten the activities of users who make, run, modify and share Free

Software.  At the same time, GPLv3 gives favorable consideration to practical

goals such as certainty and administrability for patent holders that

participate in distribution and development of GPL-covered software.  GPLv3's

policy requires each such patent holder to provide appropriate levels of

patent assurance to users, according to the nature of the patent holder's

relationship to the program.

In general, GPLv3 provides for two classes of patent commitments:

\begin{itemize}

\item Grant of license to claims in contributor versions: GPLv3~\S11

  introduces an affirmative grant of rights to patent claims by those who

  contribute code to GPL'd programs. The intent is to prevent parties from

  aggressively asserting patents against users of code those parties have

  themselves modified --- in theory preventing betrayal by ``insiders'' of

  the copyleft community.  A contributor's patent claims necessarily

  infringed by the version of the program created by the incorporation of its

  modifications are licensed to all subsequent users and modifiers of the

  program, or programs based on the program.  No patent claims only infringed

  by subsequent modifications by other parties are thus licensed.  Patent

  claims acquired after the making of the ``contributor version'' necessarily

  infringed by that version are also licensed by this provision at the time

  of their acquisition or perfection.

\item Prohibition of enforcement of patent claims against those to whom you

  distribute: GPLv3~\S10 makes explicit that licensees who directly

  distribute may not make demands for acceptance of patent licenses or

  payment of patent royalties from distribution recipients.  This provision

  establishes a uniform rule of patent exhaustion with respect to GPL'd

  programs regardless of the domestic patent law in any particular system or

  locale.

\end{itemize}

The following two subsections discuss in order each of the above mentioned

classes of patent commitments.

\subsection{The Contributor's Explicit Patent License}

Specifically, the ideal might have been for GPLv3 to feature a patent license

grant triggered by all acts of distribution of GPLv3-covered works.  The FSF

considered it during the GPLv3 drafting process, but many patent-holding

far-reaching impact of the patent license grant on the patent holder is

disproportionate to the act of merely distributing code without modification

patent assets to exercise requisite diligence in reviewing all the

GPL-covered software that it provides to others.  Some expressed particular

concern about the consequences of ``inadvertent'' distribution.

The argument that the impact of the patent license grant would be

``disproportionate'',  that is to say unfair, is not valid. Since

software patents are weapons that no one should have, and using them for

aggression against free software developers is an egregious act (thus

preventing that act cannot be unfair). 

However, the second argument seems valid in a practical sense.  A

typical GNU/Linux distribution includes thousands of programs.  It would

be quite difficult for a re-distributor with a large patent portfolio to

review all those programs against that portfolio every time it receives

and passes on a new version of the distribution.  Moreover, this question

raises a strategic issue. If the GPLv3 patent license requirements

convince patent-holding companies to remain outside the distribution

path of all GPL-covered software, then these requirements, no matter how

strong, will cover few patents. 

GPLv3 therefore makes a partial concession

which would lead these companies to feel secure in doing the

distribution themselves. GPLv3~\S11

applies only to those distributors that have

modified the program.  The other changes we have made in sections 10 and

11 provide strengthened defenses against patent assertion and compensate

partly for this concession. 

Therefore, GPLv3~\S11 introduces the terms ``contributor'', ``contributor version'', and

``essential patent claims'', which are

used in the GPLv3~\S11\P3.   Viewed from the perspective of a recipient of the

Program, contributors include all the copyright holders for the Program,

other than copyright holders of material originally licensed under non-GPL

terms and later incorporated into a GPL-covered work.  The contributors are

therefore the initial GPLv3 licensors of the Program and all subsequent

upstream licensors who convey, under the terms of GPLv3~\S5, modified covered

works.

Thus, the ``contributor version'' includes the material the contributor has copied from the

upstream version that the contributor has modified.  GPLv3~\S11\P3

 does not apply to those that redistribute the program

without change.\footnote{An implied patent license from the distributor,

however, often arises.  See \S~\ref{gpl-implied-patent-grant} in this tutorial}

In other words, the ``contributor version'' includes not just

the material added or altered by the contributor, but also the pre-existing

material the contributor copied from the upstream version and retained in the

modified version.  (GPLv3's usage of ``contributor'' and ``contribution'' should

not be confused with the various other ways in which those terms are used in

certain other free software licenses.\footnote{Cf., e.g., Apache License,

  version 2.0, section 1; Eclipse Public License, version 1.0, section 1;

  Mozilla Public License, version 1.1, section 1.1.})

Some details of the ``essential patent claims'' definition deserve special

mention.  ``Essential patent claims'', for a given party, are a subset of the

claims ``owned or controlled'' by the party.  They do include sublicensable

claims that have been licensed to the contributor by a third

party.\footnote{This issue is typically handled in other software freedom

  licenses having patent licensing provisions by use of the unhelpful term

  ``licensable,'' which is either left undefined or is given an ambiguous

  definition.}  Most commercial patent license agreements that permit

sublicensing do so under restrictive terms that are inconsistent with the

requirements of the GPL\@.  For example, some patent licenses allow the

patent licensee to sublicense but require collection of royalties from any

sublicensees.  The patent licensee could not distribute a GPL-covered program

and grant the recipient a patent sublicense for the program without violating

section 12 of GPLv3.\footnote{GPLv3 also provides an example in section 12

  that makes this point clear.}  In rare cases, however, a conveying party

can freely grant patent sublicenses to downstream recipients without

violating the GPL\@.

Additionally, ``essential patent claims'' are those patents ``that would be

infringed by some manner, permitted by this License, of making, using, or

selling the work''.  This intends to make clear that a patent claim is

``essential'' if some mode of usage would infringe that claim, even if there

are other modes of usage that would not infringe.

Finally, ``essential patent claims \ldots do not include

claims that would be infringed only as a consequence of further

modification of the work.''  The set of essential patent

claims licensed  is fixed by the

particular version of the work that was contributed.  The claim set

cannot expand as a work is further modified downstream.  (If it could,

then any software patent claim would be included, since any software

patent claim can be infringed by some further modification of the

work.)\footnote{However, ``the work'' should not be understood to be

restricted to a particular mechanical affixation of, or medium for

distributing, a program, where the same program might be provided in

other forms or in other ways that may be captured by other patent claims

held by the contributor.}

\medskip

Ideally, this contributor patent policy will result in fairly frequent licensing of patent

claims by contributors.  A contributor is charged with awareness of the fact

that it has modified a work and provided it to others; no act of contribution

should be treated as inadvertent.  GPLv3's rule also requires no more work, for a

contributor, than the weaker rule proposed by the patent holders.  Under

their rule, the contributor must always compare the entire work against its

patent portfolio to determine whether the combination of the modifications

with the remainder of the work cause it to read on any of the contributor's

patent claims.

Finally, GPLv3's explicit patent license for contributors has an interesting

and useful side effect.  When a company with a large number of such claims

acquires the program's modifier, all claims held or thereafter acquired by

the purchaser are automatically licensed under this provision.  For example,

Microsoft's acquisition of Nokia resulted in the automatic licensing of all

Microsoft patent claims now or hereafter acquired which read on any

contributor version of any GPLv3 program ever modified by Nokia.

\subsection{Conveyors' Patent Licensing}

The remaining patent licensing in GPLv3 deals with patent licenses that are

granted by conveyance.  The licensing is not as complete or far reaching as

the contributor patent licenses discussed in the preceding section.

The term ``patent license,'' as used in GPLv3~\S11\P4--6, is not meant to be

confined to agreements formally identified or classified as patent licenses.

GPLv3~\S11\P3  makes this clear by defining ``patent

license,'' for purposes of the subsequent three paragraphs, as ``any express

agreement or commitment, however denominated, not to enforce a patent

(such as an express permission to practice a patent or covenant not to

sue for patent infringement)''

The definition does not include patent licenses that arise by

implication or operation of law, because the third through fifth paragraphs

of section 11 are specifically concerned with explicit promises that purport

to be legally enforceable. The final paragraph of section 11 explicitly

preserves the availability of patent licenses arising by implication or

operation of law.

GPLv3~\S11\P5 is commonly called GPLv3's downstream shielding provision.  It

responds particularly to the problem of exclusive deals between patent

holders and distributors, which threaten to distort the free software

distribution system in a manner adverse to developers and users.  The

fundamental idea is to make a trade-off between assuring a patent license for

downstream and making  (possibly patent-encumbered) CCS publicly available.

Simply put, in nearly all cases in which the ``knowingly relying'' test is

met, the patent license will indeed not be sublicensable or generally

available to all on free terms.  If, on the other hand, the patent license is

generally available under terms consistent with the requirements of the GPL,

the distributor is automatically in compliance, because the patent license

has already been extended to all downstream recipients.  Finally, if the

patent license is sublicensable on GPL-consistent terms, the distributor may

choose to grant sublicenses to downstream recipients instead of causing the

CCS to be publicly available.  (In such a case, if the distributor is also a

contributor, it will already have granted a patent sublicense anyway, and so

it need not do anything further to comply with the third paragraph.)

Admittedly, public disclosure of CCS is not necessarily required by other

sections of the GPL, and the FSF in drafting GPLv3 did not necessarily wish

to impose a general requirement to make source code available to all, which

has never been a GPL condition.  However, many vendors who produce products

that include copylefted software, and who are most likely to be affected by the

downstream shielding provision, lobbied for the addition of the source code

availability option, so it remains.

% FIXME-LATER: This text is likely redundant and a bit confusing.  Needs work

% to use.

%% If A takes a patent license from B that benefits A only, rather than A's

%% customers or their distributees, A imposes risk from B's patents on others

%% that it does not suffer itself. Under many circumstances, this is an

%% acceptable outcome. If, however, A is the only possible source of the

%% program, by taking such a license and distributing in reliance on it, A is in

%% effect helping B to ``take the program private.''

% FIXME-LATER: end

Meanwhile, two specific alternatives to the source code availability option

are also available. The distributor may comply by disclaiming the patent

license it has been granted for the conveyed work, or by arranging to extend

the patent license to downstream recipients.\footnote{The latter option, if

  chosen, must be done ``in a manner consistent with the requirements of this

  License''; for example, it is unavailable if extension of the patent

  license would result in a violation of GPLv3~\S 12.}  The GPL is intended

to permit private distribution as well as public distribution, and the

addition of these options ensures that this remains the case, even though it

remains likely that distributors in this situation will usually choose the

source code availability option.

Note that GPLv3~\S11\P5 is activated only if the CCS is not already otherwise

publicly available.  (Most often it will, in fact, already be available on

some network server operated by a third party.)  Even if it is not already

available, the option to ``cause the Corresponding Source to be so

available'' can then be satisfied by verifying that a third party has acted

to make it available.  That is to say, the affected distributor need not

itself host the CCS to take advantage of the source code availability option.

This subtlety may help the distributor avoid certain peculiar assumptions of

liability.

Note that GPLv3~\S11\P6--7 are designed to stop distributors from colluding with

third parties to offer selective patent protection.  GPLv3 is designed to

ensure that all users receive the same rights; arrangements that circumvent

this make a mockery of free software, and we must do everything in our power