However, I can offer you a that explores the quest for such a resource — a fictional, thoughtful story about a legal translator searching for an authoritative German equivalent of Black’s, the ethical dilemmas of legal terminology across languages, and the tension between access to justice and intellectual property.
Black’s Law Dictionary Deutsch PDF: Navigating American Legal Terminology in German
While not in German, these are freely available older editions of the dictionary often used by law students and practitioners: Black's Law Dictionary 4th Edition (1968)