This book is the result of a doctoral thesis accepted by the University of Halle-Wittenberg in Germany. It was written in large part during my time as a visiting research student at Queen Mary University of London. This book takes into account the legal situation, literature and case law until August 2018. I wish to express my sincere gratitude to my doctoral thesis supervisor, Professor Dr. Christian Tietje, for his encouragement, valuable advice and the opportunity to embark on this interesting research topic. I am also thankful to Professor Dr. Dirk Hanschel who kindly undertook the second evaluation of my doctoral thesis. I especially want to thank Dr. Angelos Dimopoulos for the many fruitful discussions we had and his insightful, critical and thought-provoking comments on earlier drafts of my thesis, which greatly helped advance my work and contour my arguments. I would also like to mention the fantastic research environment at Queen Mary University and wish to thank my fellow research students for many wonderful discussions. Moreover, I am deeply thankful to my parents and my sister, Anne, for supporting me throughout my life. Finally, I want to thank Juliane dearly for being the best support one can imagine. I dedicate this book to her.