In German criminal procedural law, the limits of the powers of state authorities to apply restrictions on human rights and freedoms are determined on the basis of the principle of proportionality. The implementation of law through investigative actions represents the condition of an eventual restriction of fundamental rights, meaning that these actions are due to the presence of a legislative basis, which defines the preconditions, the essence and the limits of the application of coercive procedural measures. In the light of the conditions and grounds on which the individual’s liberty may be restricted, it is examined the principle of proportionality under the Code of Criminal Procedure of the Federal Republic of Germany.