За клевету, то есть обидную неправду - два года:
Section 186
Defamation
Whosoever asserts or disseminates a fact related to another person which may defame him or negatively affect public opinion about him, shall, unless this fact can be proven to be true, be liable to imprisonment not exceeding one year or a fine and, if the offence was committed publicly or through the dissemination of written materials (section 11(3)), to imprisonment not exceeding two years or a fine.
За обидную правду - всего лишь год:
Section 185
Insult
An insult shall be punished with imprisonment not exceeding one year or a fine and, if the insult is committed by means of an assault, with imprisonment not exceeding two years or a fine.
Section 192
Insult despite proof of truth
Proof of truth of the asserted or disseminated fact shall not exclude punishment under section 185 if the insult results from the form of the assertion or dissemination or the circumstances under which it was made.
За оскорбление покойника - два года:
Section 189
Violating the memory of the dead
Whosoever defames the memory of a deceased person shall be liable to imprisonment not exceeding two years or a fine.
http://www.gesetze-im-internet.de/englisch_stgb/englisch_stgb.html