Page "Vorstand" Paragraph 6

Formally, the power to appoint members of the Vorstand lies with the Aufsichtsrat, which can appoint members with a two-thirds majority vote of approval, or a simple majority if multiple rounds of voting are required in order to reach a decision.

Because 50 % of the members of the Aufsichtsrat are employees, this prevents employees from blocking the appointment of members of the Vorstand.