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\section*{Opinion on Covenant Not to Assert Patent Claims}


Patent licenses are legal fictions.  A patent gives its owner the power
to exclude others from practicing a claim, but it does not confer an
affirmative right to practice it.  In essence, then, a patent license is
nothing more than an undertaking not to sue the licensee, and such an
undertaking is precisely what is needed to enable users of GPL'd code to
exercise their rights without fear of liability to upstream distributors
for infringement of software patents.  In Draft 2 we replace the
formalism of the express patent license given in the first paragraph of
Draft 1, section 11 with a simpler covenant not to assert patent claims,
which more accurately describes the obligations and rights of
distributors and distributees under the GPL.

Our rewriting of the first paragraph of section 11 benefited from the
comments we received from the public and from our discussion
committees.  The scope of the express patent license was unclear to
many readers; many gave it a much broader reading than we had
intended.  The patent license operated to benefit ``any and all
versions of the covered work,'' which some read as extending well
beyond works based on the covered work to cover all ancestrally and
laterally-related works.  The set of claims that were licensed were
those that would be infringed by the distributed covered work ``or any
reasonably contemplated use of the covered work.''  The reference to
``reasonably contemplated use'' was taken from United States case law
articulating the implied patent license doctrine in a conventional
seller-buyer context.  Readers questioned whether the phrase had any
ascertainable meaning as used in our provision.

In the covenant provided in the revised section 11, the set of claims
that a party undertakes not to assert against downstream users are that
party's ``essential patent claims'' in the work conveyed by the party.
``Essential patent claims,'' a new term defined in section 0, are simply
all claims ``that would be infringed by making, using, or selling the
work.''  We have abandoned the phrase ``reasonably contemplated use.''
This change makes the obligations of distributing patent holders more
predictable.

Rather than referring ambiguously to ``any and all versions of the
covered work,'' the covenant not to assert runs in one direction along
the branches of a distribution tree that, unlike the earlier patent
license, begins explicitly with the original author.  Each licensee
receives the Program with a covenant from each author and conveyor of
the Program and any GPLv3-covered material on which the Program is
based.  The covenant is an undertaking not to bring a suit that alleges
infringement based on the licensee's exercise of any rights under the
GPL.  Each licensee conveying a covered work makes the same covenant to
all direct and remote recipients, including recipients of works based on
the covered work, with respect to that licensee's essential patent
claims in that covered work.

The covenant makes no distinction between those who convey a work
under section 4 (that is, a work in which they hold no copyright
interest) and those who convey a modified work under section 5.  Some
members of our discussion committees, commenting on the patent license
of our first draft, urged that such a distinction be made, either by
applying the patent license only to ``contributions'' or by specifying
a more limited form of patent license for mere distribution.  We do
not understand the argument that it is unreasonable for distributors
of GPL-covered code to promise not to sue their own customers, or
their customers' customers, for patent infringement arising out of
that distributed code.  Nor do we understand why the presence or
absence of modifications by the distributor ought to make any
difference.  That there are other free software licenses that limit
the operation of their patent license provisions to ``contributions''
is no reason to adopt an approach that does less to protect users from
software patents.

Like the express patent license it replaces, the covenant not to
assert patent claims is rooted in the basic principles of the GPL.
Our license has always stated that distributors may not impose further
restrictions on users' exercise of GPL rights.  To make the suggested
distinction between contribution and distribution is to allow a
distributor to demand patent royalties from a direct or indirect
recipient, based on claims embodied in the distributed code. This
undeniably burdens users with an additional legal restriction on their
rights, in violation of the license.

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