Upstream has changed the license of Authen-CAS-Client to the following:

  This software is information.
  It is subject only to local laws of physics.

This seems to me not to be distributable by Debian. Luckily, the version
we do ship (0.07) has the 'Expat' license.

I am filing this bug so that the issue becomes a bit more visible.

Maybe we shall consider removing this from Debian (popcon 222; vote 149);
or maybe somebody would want to fork.

There is one reverse dependency, libapache2-authcassimple-perl (popcon
21; vote 2), which has no reverse dependencies.

https://sources.debian.org/src/libauthen-cas-client-perl/0.08-2/Changes

  * updated to 'Nil' license

I have the impression this software is placed in the public domain
by the author (which is DFSG-compatible).

When the situation is unclear, asking the author is also an option.

cu
Adrian