It is a good tradition of legal scholars—in particular in Germany—to honour their greatest with a special book: a Festschrift for celebrating a significant birthday or—on a less pleasant occasion—a Ged€achtnisschrift after they have passed away. In the case of Horst G€unter Krenzler, it is our great and at the same time sad honour to edit this Liber amicorum in memoriam, dedicated to his life and work at the European Commission and the Ludwig Maximilians University Munich, but more than that to him as a great colleague, teacher, lawyer, scholar, liberal and European! We have tried our best to find as many former colleagues and friends of Horst Krenzler as possible and have benefitted a lot from referrals of others. We can only hope that we did not miss too many and apologise in every individual case. The contributions we were able to bring together, only with the collaboration and effort of all the contributors, try to touch upon all the matters Horst Krenzler was interested in as a lawyer, from a practical as well as a scholarly perspective. Predominantly, they treat matters of EU external relations, the common commercial policy and international economic law. Whether we have achieved to produce a book Horst Krenzler would have enjoyed reading is for others to judge. The editing of a book like this would not be possible without the help of numerous other people. We are enormously grateful to the staff of Christoph Herrmann’s Chair at the University of Passau, namely Fiona Whiteside, Viktoria Sauter and Moritz Zegowitz, who took care of all the proofreading and formatting. Thank you for your excellent work