Application and Enrollment Process
Quoting from the study and examinations regulations, from March 2017, paragraph §4
"(5) Over and above this, applicants must have adequate knowledge of the English or German language at the level of university entrance qualification. Foreign applicants must provide an internationally accepted language certificate or an equivalent proof, showing that their active and passive language skills correspond to Level C1 of the Common European Reference Framework for Language."
The following page elaborates on what the OVGU considers to be C1 level: