Adrian Lienhard wrote on Wed, 10 Mar 2010 10:19:44 +0100

> If I understand correctly Squeak 4 is Squeak 3.10.2 but with
> the MIT license tag on it even though it has hundreds of methods
> from authors that have not signed the agreement. Is this OK
> from a legal point of view? Just curious...

This is a very important question. The issue is risk management. As Alan
Kay often pointed out in the old license discussions, it is impossible
to reduce the risk of being sued to zero. No matter what you do it can
still happen. But your actions can certainly increase or reduce that
risk.

So our first step was to audit the 3.10.2 image in as much detail as we
could. I personally reread every email from the first couple of years of
Squeak, for example, and identified the authors of all changes that
happened before we had time stamps. We evaluated the work that the Etoys
group had done as well as the material that you pointed out below. We
sent out a new round of emails, which resulted in slightly increasing
the list of signed authors (the list was already slightly larger since
we got updated information from VPRI).

Originally, the amount of code from authors who hadn't signed was 478
methods and 5289 lines of code. I don't have the number after the recent
reductions, but since it isn't zero there is the risk that at some
future date somebody will say they weren't aware of the relicensing and
don't agree with it. Our policy is that in such a case we will
immediately remove the offending code. They might say that is not
acceptable and want to sue us anyway. You might imagine what the chances
of this actually happening is, and as long as it is below a certain
level we can be accepted by the SFC.

> BTW, in Pharo we rewrote or removed all dirty code. This
> is documented here in case you are interested:
> http://code.google.com/p/pharo/wiki/LicenseCleanEffort
> and http://code.google.com/p/pharo/wiki/ResultofRelicensing

Thank you very much for that work and your careful documentation of it.
That information was extremely valuable for our own effort.

-- Jecel