[License-review] ESA Permissive PL 2.3

[Carsten Gerlach]

Bruce,

please excuse the delayed response. I'm answering to your comments in
separate e-mails.

> *ESA Permissive PL 2.3*
> 3.1 _No Copyleft._
> You may Distribute the Software and/or Modifications, as Source Code or
> Object Code, under any
> license terms, provided that
> (a) notice is given of the use of the Software and the applicability of
> this License to the
> Software; and
> (b) You make best efforts to ensure that further Distribution of the
> Software and/or
> Modifications (including further Modifications) is subject to the
> obligations set forth in
> this Sec. 3.1 (a) and (b).
> 
> The title "No Copyleft" is confusing and incorrect, since the terms of
> that section actually /do /permit distribution under a copyleft license,
> and they still apply even if the downstream licensor uses a non-copyleft
> license. 

The intention is to clarify that the license itself does not include a
copyleft clause (as "no copyleft" is generally understood).
Redistribution under a copyleft license is feasible, as the software can
be redistributed "under any license terms". I would not have thought of
the title as confusing in that regard.

> The actual effect of the terms is to guarantee that whatever
> license is used, the ESA Permissive PL 2.3 license is still available as
> an /alternative license/, and the downstream licensor has to make a
> notice to that effect.
> 
> And thus, I'd suggest that you state the actual text of the notice the
> poor un-counseled Open Source developer has to make in that case. Here's
> my suggested rewrite:

This would indeed be helpful, but to achieve this, we would prefer to
suggest a notice text in the license FAQ.

> 3.1 _Continued Availability of This License._
> You may Distribute the Software and/or Modifications, as Source Code or
> Object Code, under any
> license terms, provided that
> (a) you convey this notice with the software:
> /This software contains a portion licensed under the ESA Permissive PL
> 2.3. For that portion, the ESA Permissive PL 2.3 terms are available as
> an alternative to any other license applied to this software. The
> portion was downloaded from, or is available at:
> ___________________________________________


"Contains a portion licensed under the ESA Permissive PL" might suggests
that two licenses apply simultaneously to the software. That could
prohibit a combination of ESA-PL Permissive licensed code with e.g. GPL
licensed code. I would therefore suggest the notice:
"This software contains a portion of XXX, Copyright © 2018 YYY. XXX is
originally licensed under the ESA-PL Permissive  license."

> (b) you add to the notice the online location where you downloaded the
> Software, or the location where it is currently available in Source Code
> form as separate software entirely under this license. This may be an
> online location or a subdirectory within your own software distribution.

We will suggest in the FAQ to add a pointer to the online location in
the notice as a matter of best practice, but would rather avoid such an
additional obligation in the license. Compliance with the license terms
should be as simple as possible. In most cases, the copyright notice
along with the name of the original component and author(s) should be
sufficient to find the original distribution (e.g. via search engines).

> (c) You make best efforts to ensure that further Distribution of the
> Software and/or
> Modifications (including further Modifications) is subject to the
> obligations set forth in
> this Sec. 3.1 (a), (b), and (c).
> 
> 7.1 If You have knowledge that exercising rights granted by this License
> *infringes *third party's
> intellectual property rights, including without limitation copyright and
> patent rights, You must take
> reasonable steps (such as notifying appropriate mailing lists or
> newsgroups) to inform ESA and
> those who received the Software about the infringement.
> 
> 7.2 You acknowledge that continuing to use the Software knowing that
> such use infringes third party
> rights (e.g. after receiving a third party notification of infringement)
> *would *expose you to the risk of
> being considered as intentionally infringing third party rights. In such
> event You *should *acquire the
> respective rights or modify the Software so that the Modification is
> non-infringing.
> 
> The problem here is that neither ESA nor the licensee is the court.
> Neither party can determine that the software under this license
> reliably /does /infringe upon any third party's intellectual property
> rights, /unless a court has already ruled to that effect. /Nor is any
> third-party notification actually proof of infringement unless there is
> an existing ruling. I could thus make a case that 7.1 and 7.2 apply
> /only after /a court ruling. Which is rather late for the sort of
> notification you're asking for. I'm sure counsel wants to know earlier
> than that.

"Knowledge" means positive knowledge of an infringement, for example if
the user is subject to infringement claims himself, has or gets positive
knowledge of infringement claims against a third party or if the user's
own intellectual property rights are being infringed. You could indeed
argue that a court ruling is required for positive "knowledge", unless
your own IPR is being infringed. However, a notification obligation of
any "potential infringement" would in our opinion put an unreasonable
compliance burden on the users/licensees, since any potential case must
be reported, regardless of the likelihood.
It shall only be clear that any user has to react immediately to a
reported infringement claim so that the infringement is stopped in due time.

Kind regards, Carsten