The Private Security Law 5/2014, of April 4, regulates the Function of Private Detectives in its article 37, as well as the Investigation Services in article 48 and Professional Secrecy in article 50.

Article 37 Private detectives

  • Private detectives will be in charge of the personal execution of the private investigation services referred to in article 48, by conducting inquiries in relation to people, events and private conduct.
  • In the exercise of their functions, private detectives will be obliged to:
  • Prepare the investigation reports related to the matters in charge of them.
  • Ensure the necessary collaboration with the Security Forces and Bodies when their professional actions are related to criminal acts or that may affect citizen security.
  • Ratify the content of their investigation reports before the judicial or police authorities when required to do so.
  • The exercise of the functions corresponding to private detectives will not be compatible with the functions of the rest of the private security personnel, nor with the functions of the personnel at the service of any Public Administration.
  • Private detectives will not be able to investigate crimes that can be prosecuted ex officio, and they must immediately report to the competent authority any fact of this nature that comes to their attention, and making available to them all the information and instruments that they may have obtained up to that moment.

Article 48 Private investigation services

  • The private investigation services, in charge of private detectives, will consist of carrying out the inquiries that are necessary to obtain and provide, on behalf of legitimate third parties, information and evidence on private conduct or events related to the following aspects:
  • Those related to the economic, labor, commercial, financial field and, in general, to personal, family or social life, except that which takes place in the homes or reserved places.
  • Obtaining information aimed at guaranteeing the normal development of activities that take place at fairs, hotels, exhibitions, shows, competitions, conventions, large commercial areas, large public venues or similar areas.
  • Carrying out inquiries and obtaining information and evidence relating to crimes that can only be prosecuted at the request of a party on behalf of the legitimate subjects in the criminal process.
  • The acceptance of the order of these services by the private detective offices will require, in any case, the accreditation, by the applicant of the same, of the alleged legitimate interest, which will be recorded in the hiring and investigation file that is open.
  • In no case may the intimate life of the people who spend in their homes or other reserved places be investigated, nor may personal, material or technical means be used in this type of services in such a way that they violate the right to honor, to personal or family privacy or the image itself or the secrecy of communications or data protection.
  • In the provision of investigation services, private detectives may not use or make use of means, vehicles or badges that may be confused with those of the Security Forces and Bodies.
  • In any case, the detective offices and private detectives in charge of the investigations will watch over the rights of their clients with respect to those of the investigated subjects.
  • The private investigation services will be carried out with respect to the principles of reasonableness, necessity, suitability and proportionality.

Article 50 Duty of professional reserve

  • Private detectives are obliged to keep confidentiality about the investigations they carry out, and they may not provide data or information about them other than to the persons who entrusted them and to the competent judicial and police bodies for the exercise of their functions.
  • Only through judicial injunction or police request related to the exercise of their functions in the course of a criminal investigation or a sanctioning procedure can the content of the investigations carried out by private detectives be accessed.

The reports presented by the detectives are supported by the following Jurisprudence:

Private detectives are means of evidence, commonly used and, on occasions, an instrument equipped with exclusivity for the effective control by the employer of the duties required of the worker
(Supreme Court. Judgment of November 6, 1990)