Subject: Re: termless copyright and patents
From: "Ben Tilly" <>
Date: Mon, 2 Oct 2006 21:07:08 -0700

Let me preface this with saying I am not a lawyer and this is not legal advice.

On 10/2/06, Thomas Lord <> wrote:
> There are simpler questions that we should not need to speculate
> about.   Here is an example:
>         A patentee, Alice, conveys a GPL program, Prog1,
>         whose source consists of files foo.c and bar.c.
>         A hacker, Bob, is working on Prog2.  Initially,
>         Prog2 does not infringe on any of Alice's patents.
>         Prog2 contains a file, zap.c, whose external interface
>         is identical to that of bar.c.  Indeed, if Bob replaces
>         zap.c with bar.c, copied from Prog1, then Prog2 runs
>         three times faster.
>         Bob makes such a replacement and conveys NewProg2,
>         a modified version of Prog2 that contains bar.c
>         instead of zap.c.
>         Question: under any circumstances whatsoever,
>         can Alice sue Bob, users of NewProg2, or sellers
>         of NewProg2 for violating a patent of hers?

The clarifying paragraph in the Preamble on this topic
notwithstanding, Alice might be able to sue users of NewProg2 for
running the software.  That is because running the program is
explicitly NOT a right the GPL grants, therefore restricting it is not
forbidden by the GPL v2, section 6.   But it is a right that patent
law allows Alice to control.  I think the GPL v3's grant in section 11
gives better protection in this regard.

If Alice sues Bob, users, sellers, etc for anything else, she is in
violation of the GPL.

> If the answer to that question is "yes", then very clearly the
> GPL has failed to protect Stallman's freedom's 0, 2, and 3
> (copying, modification, sharing of modifications).  The GPL had
> double failed by permitting Alice to release Prog1 which carried
> these extra restrictions.


> A related question would ask:  suppose Bob merely studies
> Alice's program and uses techniques found there?  What then?

Since NewProg3 is not now derived from Alice's program, I do not see
that the GPL offers any protection in this case.

> The examples in the questions obviously stand at the top of a
> slippery slope.  For example, if bar.c contains a string
> comparison routine and, instead of just re-using the file, Bob
> cuts and pastes individual characters to transform it into a
> memory allocator, and the memory allocator happens to infringe a
> patent of Alice's that Prog1 doesn't even come close to
> infringing, then it would be odd to say that Alice's
> infringement suit indicates a failure of the GPL.

I believe that the described procedure does not leave bar.c a
derivative under copyright law.  But suppose that you started with
bar.c and added to it to make a derivative that infringed on a new
patent.  What then?

Consider the following argument.  Section 6 says Alice cannot impose
further restrictions on the recipients' exercise of the rights granted
herein.  One of the rights granted herein is the right to make
modifications as long as section 2 is satisfied.  But if Alice sues
she is saying, "You may make any modifications you wish as long as you
don't wind up violating one of my other patents."  Therefore she is
restricting the freedom guaranteed in section 2.

It would be interesting to see this argument go to court.  I have no
idea whether it would hold up, or what the consequences would be if it
did.  (In particular can Alice say, "So I'm guilty of copyright
infringement, the amount you can collect from me for that is less than
I can get for patent infringement.)  Another question that I'm curious
about is what happens if Alice violates her own copyright license,
what recourse does Bob have?

> I honestly can't tell where on that slope the GPL is.  It sounds
> like some people believe that Bob can be sued.  I've suggested
> the reading of "exercise of your Rights under this license" that
> implies Bob can't be sued.

I agree with that reading.  Furthermore I note that the Preamble has a
clarifying paragraph on patents that strongly suggests that your
reading is what was intended.