How do you spell licence?

If you are British you spell it differently from Americans, sometimes:

As usual the American spelling rule (always use s) was less painful and arbitrary, so I (MB) went for that.

Why did you choose BSD?

We have chosen BSD licensing, for compatibility with SciPy, and to increase input from developers in industry. Wherever possible we will keep packages that can have BSD licensing separate from packages needing a GPL license.

Our choices were between:

John Hunter made the argument for the BSD license in Why we should be using BSD, and we agree. Richard Stallman makes the case for the GPL here:

How does the BSD license affect our relationship to other projects?

The BSD license allows other projects with virtually any license, including GPL, to use our code. BSD makes it more likely that we will attract support from companies, including open-source software companies, such as Enthought and Kitware.

Any part of our code that uses (links to) GPL code, should be in a separable package.

Note that we do not have this problem with LGPL, which allows us to link without ourselves having a GPL.

What license does the NIH prefer?

The NIH asks that software written with NIH money can be commercialized. Quoting from: NIH NATIONAL CENTERS FOR BIOMEDICAL COMPUTING grant application document:

A software dissemination plan must be included in the application. There is no prescribed single license for software produced in this project. However NIH does have goals for software dissemination, and reviewers will be instructed to evaluate the dissemination plan relative to these goals:

1. The software should be freely available to biomedical researchers and educators in the non-profit sector, such as institutions of education, research institutes, and government laboratories.

2. The terms of software availability should permit the commercialization of enhanced or customized versions of the software, or incorporation of the software or pieces of it into other software packages.

There is more discussion of licensing in this na-mic presentation. See also these links (from the presentation):

So far this might suggest that the NIH would prefer at least a BSD-like license, but the NIH has supported several GPL’d projects in imaging, AFNI being the most obvious example.