Rosenberg passed his Abitur in Fraustadt aged 17 after skipping one grade, he studied law at the Universities of Freiburg, Munich and Breslau (Wroclaw, Poland).
He passed his first legal exam in 1899 and received his doctorate in 1900: his dissertation concerned the burden of proof in civil law ("Die Beweislast nach der Civilprozeßordnung und dem Bürgerlichen Gesetzbuch").
The work was subsequently reprinted in five editions and strongly influenced the modern German Civil procedure law.
In 1932 Rosenberg moved to the University of Leipzig, but was dismissed in 1934 according to the Law for the Restoration of the Professional Civil Service for being Jewish.
The experienced helped persuade Roloff to abandon law for a career in music where he might be less directly implicated in the crimes of the regime, and later to join the Schulze-Boyson/Harnack (Rote Kapelle) resistance group.