This measure is possible under Estonian law.
The measure is possible in proceedings conducted for crimes which is listed in Estonian Code of Criminal Procedure art 126-1.
Code of Criminal Procedure
§ 126-1. General conditions for conduct of surveillance activities
(1) Surveillance activities are permitted on the bases provided for in this Code if collection of data by other activities or taking of evidence by other procedural operations is impossible, is impossible on time or is especially complicated or if this may prejudice criminal proceedings in the case.
§ 126-2. Bases for conduct of surveillance activities
(1) The Police and Border Guard Board, the Security Police Board, the Tax and Customs Board, the Military Police and the Prisons Department of the Ministry of Justice and prisons (hereinafter surveillance agency) may conduct surveillance activities on the following bases:
1) a need to collect information about the preparation of a criminal offence for the purpose of detection and prevention thereof;
2) the execution of an order on declaring a person a fugitive;
3) a need to collect information in confiscation proceedings pursuant to the provisions of Chapter 161 of this Code;
4) a need to collect information in criminal proceedings about a criminal offence.
(2) On the basis of the provisions of clauses (1) 1) and 4) of this section, surveillance activities may be conducted in the event of criminal offences specified in §§ 89-931, 95-97, 99, 1001, 101-104, 106-108, 110-114, 116, 118 and 120, subsection 121 (2), §§ 133-137, 1381 and 141-146, § 1573, subsections 151 (2) and (4), subsection 161 (2), §§ 162, 163, 172-179, 183-185, 187-190, 194, 195, 199 and 200, subsections 201 (2) and (3), subsections 202 (2) and (3), §§ 204, 206-214, 2161-217, 2172, 222, 227, 231-238, 241, 243, 244, 246, 250, 251, 255 and 256, clause 258 2), §§ 259, 2591 and 263, subsections 266 (2) and (4), §§ 274, 2901, 291, 2911, 294, 296, 298-299, 300, 3001, 302, 303, 310-313 and 315-3161, subsection 321 (2), §§ 326-328, 331, 3313, 333-334, 335, 336, 340 and 347, subsections 356 (1) and (3), subsections 357 (1) and (3), subsections 361 (1) and (3), subsections 364 (2)-(3), §§ 375-3762, 384, 3891, 391, 393, 394 and 3941, subsections 398 (2) and (4), subsections 3981 (2) and (4), §§ 400, 4023, 4024, 403-407, 414-416, 418, 4181, 4211, 4212, 434, 435 and 437-439, subsections 440 (3) and §§ 446 and 449 of the Penal Code.
(3) On the basis of this Code, surveillance activities may be conducted in respect of the following persons:
1) on the basis specified in clause (1) 1) of this section in respect of the person in the case of whom there are serious reasons to believe that he or she commits the criminal offence specified in subsection (2) of this section;
2) on the basis specified in clause (1) 2) of this section in respect of the person who is declared to be a fugitive;
3) on the basis specified in clause (1) 3) of this section in respect of the person who owns or possesses the assets which are the object of confiscation proceedings;
4) on the basis specified in clause (1) 4) of this section in respect of the person who is a suspect in criminal proceedings or with respect to whom there is justified reason to believe that he or she has committed or commits the specified criminal offence.
(4) The surveillance activities conducted on the basis provided for in clauses (1) 2)-4) of this section may be also conducted in respect of the person with regard to whom there is good reason to believe that he or she interacts with the person specified in clauses (3) 2)-4) of this section, communicates information to him or her, provides assistance to him or her or allows him or her to use his or her means of communication, and if the conduct of surveillance activities in respect of such person may provide the data required for the achievement of the objective of the surveillance activities.
§ 126-4. Grant of permission for surveillance activities
(1) Surveillance activities may be conducted with a written permission of the Prosecutor’s Office or a preliminary investigation judge. The preliminary investigation judge shall decide the grant of permission by an order on the basis of a reasoned application of the Prosecutor’s Office. The preliminary investigation judge shall consider a reasoned request submitted by the Prosecutor’s Office without delay and grant or refuse to grant permission for the conduct of the surveillance activities by an order.
(2) In cases of urgency, surveillance activities requiring the permission of the Prosecutor’s Office may be conducted with the permission of the Prosecutor’s Office issued in a format which can be reproduced in writing. A written permission shall be formalised within 24 hours as of the commencement of surveillance activities.
(3) In the case of immediate danger to the life, physical integrity or physical freedom of a person or to proprietary benefits of high value and requesting a permission or execution thereof on time is impossible, surveillance activities requiring the permission of a court may be conducted, in cases of urgency, with the permission of the court issued in a format which can be reproduced in writing. A written application and permission shall be formalised within 24 hours as of the commencement of surveillance activities.
(4) A permission issued in cases of urgency in a format which can be reproduced in writing shall contain the following information:
1) the issue of the permission;
2) the date and time of issue of the permission;
3) surveillance activities for which the permission is issued;
4) if known, the name of the person with regard to whom the surveillance activities are conducted;
5) the term of the permission for surveillance activities.
(5) If covert entry into a building, premises, vehicle, enclosed area or computer system is necessary for conduct of surveillance activities or in order to install or remove technical appliances necessary for surveillance, the Prosecutor’s Office shall apply for a separate permission of a preliminary investigation judge for such purpose.
(6) The duration of surveillance activities conducted with respect to a specific person on the basis provided for in clauses 1262 (1) 1), 3) and 4) of this Code in the same proceedings must not exceed one year. In exceptional cases, the Prosecutor General may authorise or apply to a court for authorisation to conduct surveillance activities for more than one year. In a criminal case dealt with under Council Regulation (EU) 2017/1939, the relevant authorization is granted, or application made, by a European Prosecutor or a European Delegated Prosecutor.
General rules of admissibility of evidence will apply. The measure has to be taken according to law and international treaties.
No specific obligations while conducting the interception but there are some restrictions to use specific information as evidence.
Code of Criminal Procedure art 126-7. Secret interception of auditory or visual information
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(2) Information which is transmitted by a person mentioned in § 72 of this Code or which is transmitted to such a person by another person and which is obtained by secret interception is not used as evidence provided the substance of such information consists in facts that have become known to the person in the course of the person’s official or professional activities, unless:
1) such a person has already provided a statement or given testimony concerning those facts or if the facts have been made public by any other method;
2) an authorisation for secret interception has been granted with respect to such a person or
3) a secret interception concerning another person shows that the person in question is committing or has committed a criminal offence.
Code of Criminal Procedure art 72. Refusing to give a statement or testify due to professional or other activities
(1) A right to refuse to give a statement or testify as a witness concerning circumstances which have become known to the witness in the course of their professional or other activities is vested in:
1) a minister of religion of a religious organisation registered in Estonia;
2) the defence counsel and the notary, unless otherwise provided by law;
3) a health care professional and a pharmacist regarding circumstances concerning the descent, artificial insemination, family or health of a person;
31) a person processing information for journalistic purposes, regarding information which makes it possible to identify their informant, except in a situation in which the taking of the evidence by other procedural operations is precluded or exceedingly complicated and the subject matter of criminal proceedings is a criminal offence for which an imprisonment of at least up to eight years' is prescribed, there is a predominant public interest for the statement or testimony to be given and the person is required to give the statement or testimony on an application or motion of the Prosecutor’s Office by order of the pre-trial investigation judge or by court order;
4) persons on whom the obligation to maintain a professional secret has been imposed by law.
(2) The right to refuse to give a statement or testify also extends to members of the professional support staff of the persons mentioned in clauses 1−3 of subsection 1 of this section.