The license for the Kawa software (except the optional JEmacs and BRL features - see below) is the X11/MIT license which is quoted below.

The software (with related files and documentation) in these packages
are copyright (C) 1996-2009  Per Bothner.

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

In the past the Kawa license was a “modified GNU GPL (General Public License)". If you find any files that contain the old license or otherwise seem to contradict the new license, please report that as a bug.

Some of the JEmacs files are based on Emacs and have a GPL license, which is incompatible with non-Free (proprietary) products. For that reason, the gnu.jemacs.* packages are not included any more in the standard .jar, or by default when building from source, to avoid surprises. To build JEmacs you have to specify the configure flag --enable-jemacs or the ant flag -Denable-jemacs=true.

Some code in gnu/brl and gnu/kawa/brl is copyright Bruce R. Lewis and Eaton Vance Management, with a modified-GPL license: no restrictions if used unmodified, but otherwise the GPL applies. These packages are no longer included by default in Kawa builds, but have to be selected with the configure flag --enable-brl or the ant flag -Denable-brl=true.

Kawa uses some math routines from fdlib’s libf77, which have a AT&T Bell Laboratories and Bellcore copyright. See the source file gnu/math/DComplex.java.

The sorting routine in gnu.xquery.util.OrderedTuples is a re-implementatiomn in Java of code copyrighted by Simon Tatham.

Some of the Scheme code in kawa/lib and gnu/kawa/slib are copyright other parties, and may have slightly different license wording, but I believe none of then contradicts the main Kawa license or impose extra restrictions. Search for the word copyright in these directories.

Some code has been converted from other languages, with permission. This includes the rationalize method in gnu/math/RatNum.java, based on an algorithm of Alan Bawden, as expressed by Marc Feeley in C-Gambit. The concepts and algorithm of gnu/text/PrettyWriter.java are converted from SBCL, which is in the public domain.