Anti-suit injunctions are orders restraining a party from commencing or continuing proceedings before a state court and can be issued by a court or arbitral tribunal. This book examines if and when anti-suit injunctions can be ordered, and it contemplates their legal conformity. It deals with jurisdictions familiar with anti-suit injunctions (e.g. England and the US) and compares these with the legal setting in Switzerland. The analysis not only relies on publicly available material, but also on confidential arbitral case law. Besides information on arbitral proceedings reported directly by arbitrators, the book takes into consideration unpublished material from proceedings conducted under the International Chamber of Commerce Rules and the International Arbitration Rules of Zurich Chamber of Commerce (now replaced by the Swiss Rules).