Tipically, Judiciary Police asks to the investigating judge to authorize the use of technical devices or means of tracking or traicing. The Judge may authorize it where there are enough evidence of its necessity and the measure is proportionate, indiciating the technical means to be used.
The measure will have a maximum duration of three months from the date they were authorized. Exceptionally, the judge may order successive extensions for the same or a shorter period up to a maximum of eighteen months.
Where there are reasons of urgency, the Judiciary Police may proceed to place it directily, with the obligation to report the investigating judge as son as posible and in any case within 24 h., who may ratify the measure taken or dismiss it under the same deadline.
General requirements:
1. principles of speciality (a measure is related to the investigation of a specific crime),
2. adequacy (the objective and subjective scope and the duration of the measure depending on its usefulness),
3. exceptional nature and necessity (where the investigation, given its nature, does not have other measures available which are less onerous to the fundamental rights of the accused, and when discovering of the facts is seriously hampered without recourse to this measure)
4. proportionality of the measure (when the detriment of the rights and interests at stake is not greater than the benefit that their adoption provides for public interest and third parties).
5. judicial authorization, specifying the technical means to be used.
6. Obligation of providers, agents and persons to provide the assistance and cooperation needed to the judge, the Public Prosecution Service, or members of the Judiciary Police appointed.