Copyright and License

[Tim Peters]

[Aahz Maruch]
> The primary purpose is to prevent someone else from asserting
> copyright.

[Tim]
> And what if they do?  If the original is public domain, anyone
> can continue using it, modifying it, etc.  Everything I've released
> in Python has been explicitly public domain, and there's been no
> downside.

[Aahz Maruch]
> This is not an area of copyright law that I have any familiarity with,
> but IIRC, the problem is that someone could theoretically prevent you
> from releasing improved versions of your code if they assert copyright.

I don't see how, provided I don't copy *their* improvements verbatim.  Once
copyright status is lost, it can't be regained:  the decision to put
something in the public domain is irrevocable.  That means nobody-- not even
me! --can ever assert copyright on something I release to the public domain.

Now somebody else can certainly pick that up and assert copyright on their
own enhancements.  But ideas are not copyrightable, so if they do something
cool to my software, I'm always free to do it myself too.  As a test case,
suppose you pick up tabnanny.py and teach it about 116 new forms of Unicode
whitespace, then copyright the result.  Then I'll clean-room implement the
same idea and release my version to the public domain again.  Then you come
up with a lot of money to hire lawyers for both of us <wink>.

> Side note: you always get copyright these days unless you explicitly
> release something into the public domain.  (Yes, Tim, I know you know
> that.)

Right, and I release stuff to the public domain precisely because I don't
want to fritter away email or face time answering questions about the
copyright or license status.  If someone wants to make a buck off it, or
even put their own name on it and pass it off as theirs, I generally don't
care.  Such actions carry dire professional consequences quite independent
of legal tomfoolery anyway.

PD isn't for all projects all the time, of course.  But I do think it's
severely underused:  when you don't care what someone does with a piece of
your work, PD is the clearest and least-hassle way to say so.

when-fighting-a-seven-headed-beast-go-for-the-leg-ly y'rs  - tim