A report in Spiegel noted that the Berlin prosecutor's office refused to pursue leads regarding a high-profile money laundering and bribery case involving an employee of the Bundesdruckerei (Federal Printing Office) because the documents were not submitted in German.
This rule is, inter alia, stipulated in § 184 GVG:
Next to German, the Sorbian minority in Germany is privileged in that, in the local communities where Sorbian is traditionally used, Sorbian is also admissible as an official language. The definition of "German" has variously been applied extensively (i.e. to include Low German, see OLG Oldenburg vom 10. Oktober 1927, Az: K 48, HRR 1928, 392) and restrictively, so that only grammatically correct High German is acceptable (as in a decision related to patent applications, see BGH, Beschluss vom 19. November 2002, Az: X ZB 23/01).
Moreover, recent legislation has sought to create court chambers for international commercial matters in which English is an official language. Specifically, these chambers are to be called into being at Superior Courts (Landgerichte) and will grant foreign lawyers standing.
At appeal, it is also possible for English to be allowed as an official language. I'm sure, as the draft legislation works its way through, we will have occasion to touch upon it again.
Back to the case at hand: State Prosecutor Ulf-Hartwig Hagemann reasoned his way to his conclusion by noting that "[h]insichtlich der in englischer und spanischer Sprache vorgelegten Dokumente weise ich darauf hin, dass die Gerichtssprache die deutsche Schriftsprache ist." (For our English readers: "With respect to the documents presented in English and Spanish, I note that the court language is the written German language." He added that the inquisitorial principle does not mean that the prosecutor's office must actively engage a translator.
If anyone, therefore, intends to file a criminal complaint in Germany in a language other than German, it would be wise to take this decision into account by having the documentary evidence which is not in German translated into the official language - unless it's Sorbian.
Of course, until the GVG reform enters into law and the path is cleared to use court chambers for international commercial matters, we urge that evidence in non-criminal proceedings be translated as well, even though English today is as ubiquitous as Latin in the Middle Ages.