Viral permissiveness

[Jeremy C. Reed]

I have seen multiple mentions on this thread about "relicensing" a BSD 
licensed code as GPL.

Nobody except the copyright owner can change the license.

If a different license is added it is only for the new code. It doesn't 
change the license for the original existing code.

The problem is when the new coder doesn't clearly identify the new code. 
The new coder can't blindly stamp another license on top of existing 
BSD-licensed code and assume that is correct or even can be honored.

The following is an attempt to explain some of this:
http://www.softwarefreedom.org/resources/2007/gpl-non-gpl-collaboration.html

"Note, however, that in a single source file it is typically very 
difficult, and often completely infeasible, to determine which parts of 
such a file are covered by permissive terms."