At the Federal Constitutional Court, different citations have been used over time. A table of equivalences can be found here.
New translations available at the Federal Constitutional Court’s website generally use the following abbreviations. Note that translations provided by other sources may differ.
Art. = Article (of the Basic Law - Grundgesetz, GG; also used in international treaties)
Example: Art. 20 GG = Article 20 of the Basic Law
§ = paragraph; article in a statute, a regulation, an ordinance and so on (often called section in common-law systems; in Germany they are called “Paragraf”)
Example: § 242 BGB ~ in most common-law systems, the equivalent would usually be cited as follows: “article (or section) 242 of the German Civil Code”
General example (taken from the Federal Constitutional Court Act):