The events of 11 September 2001 have provoked reactions to fight ter­ rorist activities in national legal orders all over the world. They have also led to significant developments in international law with respect to combating terrorism by military and non-military action. In order to study and discuss these newer developments of the worldwide cam­ paign against terrorism the Max-Planck-Institute on Comparative Pub­ lic law and International Law organized a Conference entitled «Terror­ ism as a Challenge for National and International Law", which was held in Heidelberg on 24 and 25 January 2003. In preparation of the conference national reports had been written, in which the legal developments in selected countries and legal orders be­ fore and after 11 September 2001 were analyzed. The aim was on the one hand to visualize specific problems of counter-terrorist action on the national level and on the other hand to focus on possible structural changes in the legislation of the states concerned. The national reports were used as a basis for comparative presentations at the conference which analyzed the development concerning certain subject matters, such as the definition of terrorism, human rights protection etc. To ini­ tialize the discussiop and for the examination of the theses set up in the papers renowned scholars from Germany and abroad had been asked to commentate on the presentations. This volume contains the material prepared for the conference.