The investigation should concern one of the following criminal offences (Art. 588 ter a in relationship with art.579.1 Criminal Procedural Code): a) Intentional crimes punished with a maximum of, at least, three years’ imprisonment sentence. b) Offences committed within a criminal group or organisation. c) Terrorist offences
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.
According to the Spanish Criminal Procedural Law on Data preservation order.
The Public Prosecution Service, or the Judiciary Police, may require any individual or
incorporated entity to preserve and protect specific data or information included on a
computer warehousing system which they have access to until the relevant judicial
authorisation is obtained for its assignment, in accordance with the provisions of the
preceding articles.
The data will be preserved for a maximum of ninety days, which may only be extended
once until the assignment is ordered or one hundred and eighty days have passed.
The party requested to do so will be under the obligation to cooperate with, and keep
secret, the performance of this legal measure and will be subject to the liability
described in paragraph·3 of article 588 b. v.