Private Investigators are regulated by the Law 5/2014, of 4 april, regarding Private Security:

Article 5. Private Security Activities

2. Private Investigators offices may provide, with exclusive nature, “Private investiga-tions regarding people, events or prosecutable offenses”.

Article 19

Private Investigators at the request of people or legal entities, are responsible of: Obtain and provide information and evidence of conduct or private events affecting the econo-mic, labor, commercial, financial and generally personal, family or social life sphere, except those affecting homes or reserved places. Investigation of felonies upon request of the legitimate parties in criminal proceedings crimes. Surveillance at fairs, hotels, exhibitions and similar areas.

Article 37. Private Investigators

1. Private investigators are responsible for the personal performance of private investi-gation services to which Article 48 refers, by conducting inquiries regarding people, events and private behavior.

4. Private detectives can not investigate ex officio prosecutable offenses, they must re-port immediately to the competent authority any act of this nature that come to their knowledge, and provide all the information and tools that may have obtained so far.

Article 48. Private Investigation Services

1. Services of private investigations by private investigators consist in conducting inqui-ries that are necessary for the collection and input, on behalf of legitimate third parties, of information and evidence of conduct or private events related to the following as-pects
a) Those related to economic, labor, commercial, financial sector and in general, personal, family or social life, excluding the ones that take place in homes or reserved places.
b) Obtaining information tending to ensure the normal development of activities taking place at fairs, hotels, exhibitions, shows, events, conventions, depart-ment stores, public places of grand assembly or similar areas.
c) Conducting investigations and obtaining information and evidence concerning only prosecutable crimes on behalf of persons authorized in criminal proce-edings.

2. Acceptance of the order of these services by the offices of private investigators requi-re, in any case, accreditation, by the applicant thereof, the legitimate interest alleged, that shall be recorded in the contract specifications and investigation to be opened.
3. In no case may investigate the intimate lives of people in their homes or other reser-ved places also cannot be used in this type of investigations personal means, illegal materials that violate the right to honor, personal privacy or family or image or the se-crecy of communications or data protection.
4. In providing investigation services, private investigators may not use or make use of media, vehicles or badges that may be confused with those of the Security Forces.
5. In any case, private investigators offices and private investigators in charge of inves-tigations shall ensure the rights of their clients with respect to the subjects investigated.
6. Private investigation services will be implemented with respect for the principles of reasonableness, necessity, appropriateness and proportionality.

Article 49. Investigation Reports

5. Private investigations have reserved character and the data obtained through them can only be available to the client or, where appropriate, judicial and police bodies, in the latter case for a police investigation only or for disciplinary proceedings , in accordance with Article 25.

Article 50. Duty of professional secrecy

1. Private investigators are bound to secrecy about investigations carried out, and cannot provide data or information about them to anyone rather than the people who committed them and to the relevant law enforcement bodies for the performance of their duties.
2. Only by court order or police request related to the exercise of their functions in the course of a criminal investigation or a disciplinary procedure may access the contents of the investigations carried out by private investigators.

Law 1/2000 of Civil Procedure

In the Civil Procedure Act, in section 265, Law 1/2000 of 7 January, states that the re-ports issued by private investigators have qualified testimony character and cannot be challenged by the other party if ratified in court.

The Supreme Court defines private investigators as privileged witnesses in justice courts.

Judgment 17467/1990:

“The testimony issued by private investigators has, for his truthfulness, not only guarantee required professionalism and, in principle, presumably in a profession legally regulated, but which, undeniably, provides accurate and continuous dedication to the object of further testimony to issue and additional accreditations, graphics or sound, that latter usually accompanied.”