Terrorism has become one of the major issues of international criminal law policy. A sudden change of public perception of terrorism has occurred since 9/11 attacks – from regional groups of fundamentalists, terrorists have become an international threat to worldwide security. This fact has profoundly influenced anti-terrorist policies – from responsive actions to rather preventive and forward-looking strategies. As the opposing values of national security and civil liberties render the criminal justice response to be so complex to introduce, this work underlines the significance of balance and proportionality in waging a war on terror. Moreover, an evaluation of legislative mechanisms introduced by the United Nations police makers as well as those adopted in Germany, Poland and Great Britain will be made. Lastly, the work outlines the most common impediments that befall the investigation and prosecution of terrorists. By taking the aforementioned aspects into consideration, it will be determined which fundamental features will most effectively ensure an adequate criminal justice response and preserve the civil liberties derived from the principle of a democratic state ruled by law.