in german law it's even impossible to transfer copyright (Urheberrecht). There is but one way: inheriting. What can be transferred though is usage right - licensing.
Many Germans incorrectly believe that copyrights cannot be abandoned. The actual situation in German law is as follows:
"Nutzungsrechte" (literally "usage rights") include the rights of copying, modification, distribution, etc. These rights can be waived, as in other countries.
"Urheberrechte" (literally "originator rights") include reputation rights and generally cannot be waived. This protection against fraud, libel, etc. has nothing to do with whether something is in the public domain.
