Over recent years, most of the criminal justice systems in Europe have witnessed a tendency to enhance the role of pre-trial inquiries. Different kinds of pre-trial measures have had a heavy impact on the fundamental rights of individuals involved in criminal procedures. This book contains a comparative study of four European countries on pre-trial precautionary measures limiting personal liberty. This comparison is part of two general frameworks concerning the ECt HR case-law and the EU legislation in the field of the right to liberty and security. In its two level approach, the book provides a critical guide for understanding the most significant changes which occurred in the area of liberty and security in the pre-trial phases of criminal proceedings as well as the protection systems developed in Europe both at national and supranational level to face the new challenges of the modern criminal investigation.