Official works enjoy no protection in terms of copyright law.

(1) Laws, ordinances, official decrees and notices as well as decisions and official guidelines on decisions have no copyright protection.
(2) The same applies to other official works that have been published in the official interest for general information, with the restriction that the provisions on prohibition of changes and references in § 62 paragraph 1 to 3 and § 63 paragraph 1 and 2 accordingly are to be applied.
(3) The copyright in private standards is not affected by paragraphs 1 and 2 if laws, ordinances, decrees or official notices refer to them, without reproducing their wording. In this case, the author is obliged to grant each publisher the right to reproduce and distribute on reasonable terms. If a third party owns the exclusive right for duplication and distribution, then this is obligated to grant the right of use according to sentence 2.

Source: www.gesetze-im-internet.de/urhg/__5.html