The European Commission is allowed to conduct extensive investigations in EU antitrust proceedings. The companies involved, on the other hand, have very limited rights of defense. They must respond to the Commission's inquiries, even if this means providing evidence of their own violations of antitrust law. European courts also support this interpretation of the procedural rules. Constantly increasing fines exacerbate the situation. Furthermore, the boundaries between permissible behavior and violations are often poorly defined for companies. However, does the right to refuse testimony for companies not arise from European fundamental rights, particularly from the Charter of Fundamental Rights in the Treaty of Lisbon? Dominik Becker examines this important question of European and antitrust law. He also clarifies how affected parties can enforce fundamental rights guarantees at the EU level in court.