[Twisted-Python] Twisted is now under the MIT license.

Glyph Lefkowitz glyph at divmod.com
Thu Aug 26 07:30:26 MDT 2004

(Aside to TMLabs: I think there may have been a miscommunication.  You
*may* continue to consign copyright either to me or to another TML
member if you would like to.  The advantage would be to legally disclaim
any interest in conversations like this one :-) )


I am not a lawyer.  As far as I know, you are not a lawyer.  These
discussions only have real meaning between legal professionals in a
specific jurisdiction at a specific point in time.  Even then, there are
many subtle points open to debate.  Still, I'll state my intentions and
my understanding of the law for the record, in case someone wants to
refer back to this when they're suing us all.

I'm sorry I didn't post something before the change, but this change
really shouldn't affect anyone except those who need a more flexible
license for Twisted than the LGPL.  Since those people previously had to
contact me personally, I am pretty sure there are not many of them :).
I will try to answer as many possible objections in this email, even
those you have not raised, since I have seen some discussion on the list
and I anticipate more.  Unless I have overlooked something really
serious, though, this is the the last message I'll write on the subject;
after years of doing it, I really hate talking about licensing.

I have asked several intellectual property lawyers and paralegals
questions related to this, and have gotten at least two interpretations
per person.  US copyright law and the Berne convention, as they apply to
software and to jointly authored works by hobbyists, are very confusing.
One radical point of view is that in some contexts, copyright law cannot
apply to software at all.  I do not believe that there is a "correct"
solution that gives an air-tight legal protection, given the very nature
of international law.

However, I have attempted to follow a commonly accepted practice within
the open source community based on my layman's view of the common
interpretation of US copyright law and the Berne convention.

The motivation for the change is simple: some people who wanted to
contribute to Twisted were in a position where they weren't able to
contribute code because they are allowed to publish open-source code
under a license of their choice, but they are not allowed to consign
their copyrights.  Furthermore, my previous motivation for making
Twisted LGPL and centralizing the copyright is no longer valid.  I don't
work in the games industry any more, and "open source" has been endorsed
by IBM and other corporate giants.  (If this doesn't make sense, google
around for old mailing-list messages where I explained the motivation
for the previous policy in depth.)

The only legal protection we are currently seeking with the licensing
Twisted 2.0 codebase, the first public release this change will affect,
is not to get sued when things go wrong with Twisted: if it breaks, you
can keep both pieces.

The reason we have a license at all is that there seems to be widespread
agreement that putting software in the public domain can leave the
original authors open to arbitrarily large liability claims, if it's a
legally valid thing to do at all.  I don't believe there is any case
history about this *specifically*, but it is a common caution so I
assume there must be other precedents.

That is the ONLY thing the license is for.  The assurances that some
users may want - "will some disgruntled author on the Twisted team sue
me?" or "has the code been properly vetted for copyright violations of
others' work?" - cannot be granted by the license agreement.

I'd like to stress that.  There are no assurances.  There is no
PARTICULAR PURPOSE.  If we lie to you about who wrote it, when it was
written, why it was written or even what it is, the liability, and the
responsibility for discovering this, is yours.  This is true of close to
99% of all free/open source software, so if you don't like it, you are
going to have to find someone to take the liability for you and pay them
to do it.

(Actually it's true of proprietary, commercial software too.  Read your
Microsoft, Apple, or Adobe license agreements, if you have any.)

That said, there are mechanisms in place to prevent this kind of
"tainting" from happening.  Professionally, it would certainly be a
problem for me if it did.  I have personally made sure that everyone
with commit access understands their responsibilities.  We try very hard
to keep our hands clean.  If we fail, SVN keeps a pretty complete
history of what's happened recently, we have backups of the repository
available if there are any hardware failures.  So, while it is possible
that we will make a mistake, but it is vanishingly unlikely that we will
not be able to correct it immediately.  It is also unrelated to the
license agreement.

I also, personally, don't plan to sue anybody for using Twisted, if they
don't sue me first - though I can't speak for anyone else involved.  (Of
course, they could have sued you under the previous policy.  And I might
sue you for something else.  So again - this changes nothing.)

On Wed, 2004-08-25 at 23:51 -0400, Sergio Trejo wrote:

> If its true that Twisted Matrix Laboratories is neither a human or an 
> artificial person in any territory, then I think its a major issue not a 
> minor one.

Major issue for whom?  I don't believe that this is a problem for me,
since as I understand it it's perfectly legal, and I don't see how it
could be a problem for you, since you are getting no warranty or
agreement from Twisted Matrix Labs - whether it is real or not - only
some rights and some code.

> Copyright is not assignable to a ghost or a shadow.

Why not?  The coder at http://www.hymn-project.org/ labels the code
simply "Copyright 2004." so it seems that some people think copyright is
assignable to nobody at all...

Copyright is, however, definitely assignable to "an abbreviation by
which the name can be recognized, or a generally known alternative
designation of the owner".  Given that we are moving Twisted to be a
joint-copyright work, rather than an individually assigned work, the
collective who owns the copyright is a loose collaboration of
individuals over the internet, and a "generally known alternative
designation" for that group (without listing everyone's name in every
file) is Twisted Matrix Labs.  It would be equally reasonable to say
"Copyright http://www.twistedmatrix.com/" but that seems a tad nerdy
even for source code.

Secondly, even if I'm completely wrong about the way joint copyright
works, the copyright is assigned by the act of creating and publishing a
work, NOT by placing a copyright notice on it.  This is one of the
clearest points of agreement in all interpretations of copyright law
that I'm aware of.  Copyright notices are a holdover from laws made in
the mid-70s; they are almost meaningless for new works today.

The "work" in question here is the Twisted distribution, not individual
source files.  If for some reason we need to audit an individual's
contributions, tracking them at the file level may not be meaningful,
and we can already do that without adding the gross level of clutter
previously present in every file.  'svn blame' will allow us to track
credit to individual lines, and individual versions.  Any more
granularity than that will probably require time in court - and hey, SCO
has taught us that if you get to that point, your opponent is probably
just perjuring themselves anyway.

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