Skip to content

E. Call Data Records

Definition

Call Data Records (CDRs) are defined as metadata that do not contain the content of any communications, but solely provide information about them, such as the source and destination phone numbers, date and time of phone calls and text messages, the type of communication, the duration of phone calls, the IMEI number1 of the handset relevant to the communications, and the cell sectors2 engaged at the beginning and end of a call.3

Call Sequence Tables (CSTs) are spreadsheets or database tables which organise and present relevant information from the CDRs into an intelligible and readable format without altering the content of the CDRs.4

E1. The relevant data should be extracted from Call Data Records and presented in a readable format as Call Sequence Tables.

Keywords

extraction; format

Call Data Records (CDRs) are themselves voluminous and, without extraction of the relevant data into a readable format, meaningless.5 The STL Trial Chamber in Ayyash et al declined to admit CDRs given that they were so voluminous and unwieldy, comprising billions of entries, and unreadable in their raw form as long strings of numbers and symbols.6

Instead, the CDRs should be rendered intelligible through Call Sequence Tables (CSTs). The STL Prosecution in Ayyash et al produced a CST presenting a chronological sequence of calls relating to a target telephone number over a specified period of time, comprising relevant CDR information including: the other telephone number in contact with the target telephone number, the time and date of the call, the type of call and duration, the IMEI number7 of the handset used by the target number, and the cell identity and cell sector name of the cell sector used by the target number at the start and end of the call.8 In contrast to the CDRs, the STL Trial Chamber admitted the CSTs into evidence.9

Keywords

disclosure

Disclosure of CDRs and CSTs. The Prosecution is only required to provide the entirety of the Call Data Records (CDRs) in its custody in the formats it received them in; they are not required to prepare and disclose all CDRs as harmonised, searchable, or analysed Call Sequence Tables (CSTs).10 It is only required to disclose CSTs where available, in the format created as part of its analysis of the original raw CDRs. The MICT Single Judge in Turinabo et al distinguished the ICTR Karemera et al11 and ICTY Mladić12 cases where the Prosecution was additionally required to provide 'descriptive indices', as those cases concerned the disclosure of exculpatory material under Rule 68 of the ICTR and ICTY Rules of Procedure and Evidence,13 whereas the Defence in the Turinabo et al case had not demonstrated that the material sought was prima facie exculpatory.14

Disclosure of Related Documents. Pursuant to Rule 71(B) of the IRMCT Rules of Procedure and Evidence, the Prosecutor shall permit the Defence to inspect any books, documents, photographs, and tangible objects in the Prosecutor's custody or control which are material to the preparation of the defence or intended for use at trial.15 This establishes the scope of the Prosecutor's disclosure obligations. The MICT Single Judge in Turinabo et al held that in addition to the CDRs, the following related documents fell within the scope of the disclosure obligation: correspondence with the Rwandan authorities in relation to the identification and transmission of intercepts, including requests for assistance from the Rwandan authorities, written follow-ups, the responses thereto, and the clearance letter through which the Rwandan authorities consented to the disclosure of the call logs, as these documents could be relevant to the Defence's investigation regarding the origin, nature, or the timing of the call logs and thus assist their preparation.16

Material Outside Scope of Disclosure Obligation. Pursuant to Rule 76(A) of the IRMCT Rules of Procedure and Evidence, reports, memoranda, or other internal documents prepared by a party in connection with the investigation, preparation, or presentation of the case are not subject to disclosure obligations.17 The MICT Single Judge in Turinabo et al decided that internal notes and mission reports concerning the intercepted communications were not subject to disclosure where the Defence has not demonstrated that any of the information sought might prima facie be exculpatory.18

E3. Call Data Records and Call Sequence Tables can be used in relation to other communications evidence or relied upon in their own right.

Keywords

relevance; corroboration

Call Data Records (CDRs) and Call Sequence Tables (CSTs) (collectively, 'call data') may be tendered in relation to other communications evidence. For example, they may be tendered together with intercepted communications to provide the metadata associated with those intercepted communications. The call data can be used to corroborate or discount other communications evidence. The ICC Trial Chamber in Bemba et al found that call data reinforced and confirmed the accuracy of the intercepted communications as they were consistent with each other.19 Conversely, the Defence in Nzabonimpa et al before the MICT sought to use call data to discount the reliability of intercepted communications by highlighting discrepancies between the durations of the intercepted communications and the durations of the phone calls indicated in the call data.20

CDRs and CSTs can also be relied upon in their own right to support factual assertions.21 For example, call data can demonstrate that a number of target telephones were organised and operated as a closed group in a closed network, which in turn supports charges of co-perpetration or conspiracy.22 The STL Prosecution in Ayyash et al relied upon CSTs to show that groups of target telephones were used for the planning and preparation of the alleged attack and assassination of former Prime Minister Hariri and other related acts.23

E4. The reliability of Call Sequence Tables depends on the authenticity of the underlying Call Data Records and must be proven through the presentation of expert witnesses.

Keywords

probative value; reliability; expert witnesses; authenticity

Reliability of Underlying CDRs. Call Data Records (CDRs) are the primary material on which Call Sequence Tables (CSTs) are based. Thus, before assessing the probative value of the CSTs, the Court must be satisfied with the reliability of the underlying CDRs.24 This may not require the admission into evidence of the CDRs themselves; the coded nature of CDRs means that their content is of no practical utility in its raw form.25 Instead, the tendering party should provide contextual evidence on its chain of custody, including evidence on the creation, storage, and retrieval of the CDRs.26 The CDRs themselves may also have inherent indicia of authenticity, such as the corporate watermarks of the telecommunications provider.27 For example, some of the CDRs tendered in Bemba et al had a 'kpn Group Belgium' watermark.28

Reliability of CSTs. The tendering party must also provide contextual evidence about the CSTs, particularly on how they were produced.29 Tendered CSTs must be accompanied by witness statements or testimony about who prepared the CSTs and in what manner.30 In Ayyash et al, STL Prosecution analysts described the process of creating the CSTs from the CDRs, including the method used, the peer review process, and the correction of errors in the CSTs; and a Prosecution administrator testified about receiving, storing, and processing raw call data and the design, implementation, maintenance, and repair of a database used for the analysis of the CDRs.31

When the call data is tendered together with, and in relation to, intercepted communications, the two categories of evidence are mutually reinforcing and confirm the accuracy of the other.32 The ICC Trial Chamber in Bemba et al held that it was not necessary for the Prosecution to provide further testimonial evidence on the authenticity of the call data33 in addition to the evidence already tendered, which included call data with inherent indicia of authenticity, such as the presence of the corporate watermarks of the telecommunications provider or self-identification at the start of intercepted calls;34 intercepted communications which matched the corresponding call data;35 expert testimony on the origins of the CDRs;36 and a case record containing information confirming the authenticity and chain of custody of the CDRs.37

E5. The collection and transfer of Call Data Records will not constitute a violation of international human rights standards regarding privacy if the collection and transfer are provided for by law, necessary, and proportionate.

Keywords

prejudice; privacy; data collection; data transfer

Pursuant to Article 69(7) of the Rome Statute, evidence obtained by means of a violation of internationally recognised human rights shall not be admissible if the admission would be antithetical to and would seriously damage the integrity of the proceedings. The collection and transfer of Call Data Records (CDRs) may infringe the right to privacy, but would not constitute a violation of the right if it is provided for by law, necessary, and proportionate.38 This Guideline refers to the collection or transfer of the CDRs for prosecution; CDRs are routinely and legally generated and retained by telecommunications companies in the normal course of business for billing and systems management purposes.39

Lawful Basis. There must be a lawful basis for the collection and transfer of the CDRs. Where this concerns the transmission of a request for cooperation from the Prosecutor to the relevant national authority, the Court will distinguish between two distinct legal issues: first, the authority to transmit the request for cooperation to the relevant national authority, and second, the national authority's subsequent authorisation to carry out the requested collection.40 The former is based on the Prosecutor's powers with respect to investigations under Article 54(3) of the Rome Statute or the Court's authority to make requests to States Parties for cooperation under Article 87(1) of the Rome Statute, whereas the latter is regulated by the domestic law applicable to the national authority.41

Other legal grounds are available. For example, the ICC Appeals Chamber in Bemba et al held that the legal basis for the collection of Detention Centre call data was Regulation 174 of the Regulations of the Registry concerning the monitoring of telephone calls of persons detained at the ICC Detention Centre.42 The STL Trial Chamber in Ayyash et al held that the legal basis for the transfer of CDRs was the legal framework of cooperation between the STL and the Lebanese authorities under UN Security Council Resolutions 1595 and 1757 read with Article 48(1) of the UN Charter, Article 15(1) of the Agreement annexed to UN Security Council Resolution 1757, Rules 14 and 61 of the STL Rules of Procedure and Evidence, the Memoranda of Understanding between the STL and the Lebanese authorities, and Lebanese law on intercepted communications.43

Necessity. The collection of the CDRs must be necessary for the case. It would not be necessary if other reasonable measures were available to obtain the information.44 The ICC Trial Chamber in Bemba et al held that the collection of the CDRs were necessary as they 'may be of essence for the Prosecution to be able to shed further light on the relevant facts'.45 Similarly, the STL Trial Chamber in Ayyash et al held that the transfer of CDRs were necessary as without the CDRs, the Prosecutor could not have identified and established the relevant Call Sequence Tables (CSTs) with which to construct the case and file the indictments against the accused.46

Proportionality. The proportionality of the collection of the CDRs is assessed with reference to a number of factors. In Bemba et al, the collection of CDRs was held by the ICC Trial Chamber to be proportionate because they only concerned non-privileged calls and not calls that were protected by attorney-client privilege.47 In concluding that the transfer of CDRs was proportionate, the STL Trial Chamber in Ayyash et al considered the gravity of the attack under investigation, the overall unstable security situation, and the fact that the investigation was conducted pursuant to a UN Security Council Resolution under Chapter VII of the UN Charter;48 and it noted that access to the CDRs was strictly limited to individuals who had professional and ethical obligations of confidentiality, thus minimising the intrusion to any right to privacy.49

  1. Every mobile telephone handset has a unique International Mobile Station Equipment Identity (IMEI) number: Prosecutor v Ayyash et al (Decision on Prosecution Rule 154 Motion for the Admission of Documents Relating to Telephone Subscriber Records from the Alpha Company) STL-11-01/T/TC (3 May 2016) (TC) [2], fn 9. ↩

  2. Cell sectors refer to longitudinal and latitudinal coordinates of cell tower locations and provide an indication of the approximate location where a mobile telephone handset was used for each phone call. Cell identity and cell sector names identify the cell sector used for each phone call: Prosecutor v Ayyash et al (Prosecution Motion For the Admission of Red Network-Related Call Sequence Tables and Related Statement) STL-11-01/T/TC (28 January 2015) (TC) [12], fn 6. ↩

  3. Prosecution v Ayyash et al (Judgment) TL-11-01/T/TC (18 August 2020) (TC) [373]; Prosecutor v Ayyash et al (Decision on Appeal by Counsel for Mr Oneissi Against the Trial Chamber's Decision on the Legality of the Transfer of Call Data Records) STL-11-01/T/AC (28 July 2015) (AC) [3]. See the STL Primer on Telecommunications Evidence for an accessible overview of the technical terms and concepts. ↩

  4. Prosecutor v Ayyash et al (Prosecution Motion For the Admission of Red Network-Related Call Sequence Tables and Related Statement) STL-11-01/T/TC (28 January 2015) (TC) [4]. ↩

  5. Prosecutor v Ayyash et al (Decision on Five Prosecution Motions on Call Sequence Tables and Eight Witness Statements and on the Legality of the Transfer of Call Data Records to UNIIIC and STL's Prosecution) STL-11-01/T/TC (6 May 2015) (TC) [113]. ↩

  6. Prosecution v Ayyash et al (Judgment) TL-11-01/T/TC (18 August 2020) (TC) [375], [378]. ↩

  7. Every mobile telephone handset has a unique International Mobile Station Equipment Identity (IMEI) number: Prosecutor v Ayyash et al (Decision on Prosecution Rule 154 Motion for the Admission of Documents Relating to Telephone Subscriber Records from the Alpha Company) STL-11-01/T/TC (3 May 2016) (TC) [2], fn 9. ↩

  8. Prosecutor v Ayyash et al (Decision on Five Prosecution Motions on Call Sequence Tables and Eight Witness Statements and on the Legality of the Transfer of Call Data Records to UNIIIC and STL's Prosecution) STL-11-01/T/TC (6 May 2015) (TC) [2]. ↩

  9. Prosecution v Ayyash et al (Judgment) TL-11-01/T/TC (18 August 2020) (TC) [376]. ↩

  10. Prosecutor v Turinabo et al (Decision on Jean de Dieu Ndagijimana's Urgent Motion for Disclosure of Harmonised Call Data Records) MICT-18-116-PT (2 September 2019) (Single Judge) 2. ↩

  11. Prosecutor v Karemera et al (Decision on Interlocutory Appeal Regarding the Role of the Prosecutor's Electronic Disclosure Suite in Discharging Disclosure Obligations) ICTR-98-44-AR73.7 (30 June 2006) (AC) [10], [15]. ↩

  12. Prosecutor v Mladić (Decision on Defence interlocutory appeal against the Trial Chamber's decision on EDS disclosure methods) IT-09-92-AR73.2 (28 November 2013) (AC) [27]. ↩

  13. cf Rule 73 of the IRMCT Rules of Procedure and Evidence, Article 67(2) of the Rome Statute. ↩

  14. Prosecutor v Turinabo et al (Decision on Jean de Dieu Ndagijimana's Urgent Motion for Disclosure of Harmonised Call Data Records) MICT-18-116-PT (2 September 2019) (Single Judge) 2-3, fn 12. ↩

  15. cf Rule 77 of the ICC Rules of Procedure and Evidence. The provisions mirror each other closely. ↩

  16. Prosecutor v Turinabo et al (Decision on Requests for Disclosure of Information Arising from Interviews with Investigator Tomasz Blaszczyk) MICT-18-116-PT (7 May 2020) (Single Judge) 4-5, 7. ↩

  17. cf Rule 81(1) of the ICC Rules of Procedure and Evidence. The provisions mirror each other closely. ↩

  18. Prosecutor v Turinabo et al (Decision on Requests for Disclosure of Information Arising from Interviews with Investigator Tomasz Blaszczyk) MICT-18-116-PT (7 May 2020) (Single Judge) 6. The disclosure of exculpatory evidence is governed by Rule 73 of the IRMCT Rules of Procedure and Evidence, cf Article 67(2) of the Rome Statute. ↩

  19. Prosecutor v Bemba et al (Judgment pursuant to Article 74 of the Statute) ICC-01/05-01/13-1989-Red (19 October 2016) (TC VII) [218], [224]. ↩

  20. Prosecutor v Nzabonimpa et al (Judgment) MICT-18-116-T (25 June 2021) [43], fn 145. However, this was unsuccessful as the Single Judge accepted expert evidence that the discrepancies were unlikely to have arisen from manipulation or fabrication and could have been due to differences in the recording method: [57]. ↩

  21. Prosecutor v Ayyash et al (Decision on the Prosecution Motions for the Admission of the Call Sequence Tables Related to the Five Colour-Coded Mobile Telephone Groups and Networks) STL-11-01/T/TC (31 October 2016) (TC) [44]. ↩

  22. Prosecutor v Ayyash et al (Decision on the Prosecution Motions for the Admission of the Call Sequence Tables Related to the Five Colour-Coded Mobile Telephone Groups and Networks) STL-11-01/T/TC (31 October 2016) (TC) [44]. ↩

  23. Prosecutor v Ayyash et al (Decision on the Prosecution Motions for the Admission of the Call Sequence Tables Related to the Five Colour-Coded Mobile Telephone Groups and Networks) STL-11-01/T/TC (31 October 2016) (TC) [4]. ↩

  24. Prosecutor v Ayyash et al (Decision on Five Prosecution Motions on Call Sequence Tables and Eight Witness Statements and on the Legality of the Transfer of Call Data Records to UNIIIC and STL's Prosecution) STL-11-01/T/TC (6 May 2015) (TC) [68]. ↩

  25. Prosecution v Ayyash et al (Judgment) TL-11-01/T/TC (18 August 2020) (TC) [375]; Prosecutor v Ayyash et al (Decision on Five Prosecution Motions on Call Sequence Tables and Eight Witness Statements and on the Legality of the Transfer of Call Data Records to UNIIIC and STL's Prosecution) STL-11-01/T/TC (6 May 2015) (TC) [113]. ↩

  26. Prosecutor v Ayyash et al (Decision on Five Prosecution Motions on Call Sequence Tables and Eight Witness Statements and on the Legality of the Transfer of Call Data Records to UNIIIC and STL's Prosecution) STL-11-01/T/TC (6 May 2015) (TC) [112]. ↩

  27. Prosecutor v Bemba et al (Judgment pursuant to Article 74 of the Statute) ICC-01/05-01/13-1989-Red (19 October 2016) (TC VII) [219]. ↩

  28. Prosecutor v Bemba et al (Judgment pursuant to Article 74 of the Statute) ICC-01/05-01/13-1989-Red (19 October 2016) (TC VII) [219], fn 232. ↩

  29. Prosecution v Ayyash et al (Judgment) TL-11-01/T/TC (18 August 2020) (TC) [378]; Prosecutor v Ayyash et al (Decision on Five Prosecution Motions on Call Sequence Tables and Eight Witness Statements and on the Legality of the Transfer of Call Data Records to UNIIIC and STL's Prosecution) STL-11-01/T/TC (6 May 2015) (TC) [115]. ↩

  30. Prosecutor v Ayyash et al (Judgment) STL-11-01/T/TC (18 August 2020) (TC) [379]. ↩

  31. Prosecutor v Ayyash et al (Decision on Four Prosecution Motions on Call Sequence Tables Related to Salim Jamil Ayyash, Hassan Habib Merhi, Assad Hassan Sabra, Mustafa Amine Badreddine, and Five Witness Statements) STL-11-01/T/TC (31 October 2016) (TC) [88]. ↩

  32. Prosecutor v Bemba et al (Judgment pursuant to Article 74 of the Statute) ICC-01/05-01/13-1989-Red (19 October 2016) (TC VII) [218]. ↩

  33. Prosecutor v Bemba et al (Judgment pursuant to Article 74 of the Statute) ICC-01/05-01/13-1989-Red (19 October 2016) (TC VII) [225]. ↩

  34. Prosecutor v Bemba et al (Judgment pursuant to Article 74 of the Statute) ICC-01/05-01/13-1989-Red (19 October 2016) (TC VII) [219]. ↩

  35. Prosecutor v Bemba et al (Judgment pursuant to Article 74 of the Statute) ICC-01/05-01/13-1989-Red (19 October 2016) (TC VII) [220]. ↩

  36. Prosecutor v Bemba et al (Judgment pursuant to Article 74 of the Statute) ICC-01/05-01/13-1989-Red (19 October 2016) (TC VII) [221]. ↩

  37. Prosecutor v Bemba et al (Judgment pursuant to Article 74 of the Statute) ICC-01/05-01/13-1989-Red (19 October 2016) (TC VII) [222]. ↩

  38. Prosecutor v Bemba et al (Decision on Bemba and Arido Defence Requests to Declare Certain Materials Inadmissible) ICC-01/05-01/13-1432 (30 October 2015) (TC VII) [14], see fn 20 for references to European Court of Human Rights jurisprudence; Prosecutor v Ayyash et al (Decision on Five Prosecution Motions on Call Sequence Tables and Eight Witness Statements and on the Legality of the Transfer of Call Data Records to UNIIIC and STL's Prosecution) STL-11-01/T/TC (6 May 2015) (TC) [108]. ↩

  39. Prosecutor v Ayyash et al (Decision on Five Prosecution Motions on Call Sequence Tables and Eight Witness Statements and on the Legality of the Transfer of Call Data Records to UNIIIC and STL's Prosecution) STL-11-01/T/TC (6 May 2015) (TC) [2]. ↩

  40. Prosecutor v Bemba et al (Judgment on the appeals of Mr Jean-Pierre Bemba Gombo, Mr Aimé Kilolo Musamba, Mr Jean-Jacques Mangenda Kabongo, Mr Fidèle Babala and Mr Narcisse Arido against the Decision of Trial Chamber VII entitled "Judgment pursuant to Article 74 of the Statute") ICC-01/05-01/13-2275-Red (8 March 2018) (AC) [452]. ↩

  41. Prosecutor v Bemba et al (Judgment on the appeals of Mr Jean-Pierre Bemba Gombo, Mr Aimé Kilolo Musamba, Mr Jean-Jacques Mangenda Kabongo, Mr Fidèle Babala and Mr Narcisse Arido against the Decision of Trial Chamber VII entitled "Judgment pursuant to Article 74 of the Statute") ICC-01/05-01/13-2275-Red (8 March 2018) (AC) [453], [481]. ↩

  42. Prosecutor v Bemba et al (Judgment on the appeals of Mr Jean-Pierre Bemba Gombo, Mr Aimé Kilolo Musamba, Mr Jean-Jacques Mangenda Kabongo, Mr Fidèle Babala and Mr Narcisse Arido against the Decision of Trial Chamber VII entitled "Judgment pursuant to Article 74 of the Statute") ICC-01/05-01/13-2275-Red (8 March 2018) (AC) [374]. ↩

  43. Prosecutor v Ayyash et al (Decision on Five Prosecution Motions on Call Sequence Tables and Eight Witness Statements and on the Legality of the Transfer of Call Data Records to UNIIIC and STL's Prosecution) STL-11-01/T/TC (6 May 2015) (TC) [100]-[101], fns 156-158. ↩

  44. Prosecutor v Bemba et al (Decision on Bemba and Arido Defence Requests to Declare Certain Materials Inadmissible) ICC-01/05-01/13-1432 (30 October 2015) (TC VII) [16]. ↩

  45. Prosecutor v Bemba et al (Decision on Bemba and Arido Defence Requests to Declare Certain Materials Inadmissible) ICC-01/05-01/13-1432 (30 October 2015) (TC VII) [16]. ↩

  46. Prosecutor v Ayyash et al (Decision on Five Prosecution Motions on Call Sequence Tables and Eight Witness Statements and on the Legality of the Transfer of Call Data Records to UNIIIC and STL's Prosecution) STL-11-01/T/TC (6 May 2015) (TC) [103], [109]. ↩

  47. Prosecutor v Bemba et al (Decision on Bemba and Arido Defence Requests to Declare Certain Materials Inadmissible) ICC-01/05-01/13-1432 (30 October 2015) (TC VII) [17]. ↩

  48. Prosecutor v Ayyash et al (Decision on Five Prosecution Motions on Call Sequence Tables and Eight Witness Statements and on the Legality of the Transfer of Call Data Records to UNIIIC and STL's Prosecution) STL-11-01/T/TC (6 May 2015) (TC) [103]. ↩

  49. Prosecutor v Ayyash et al (Decision on Five Prosecution Motions on Call Sequence Tables and Eight Witness Statements and on the Legality of the Transfer of Call Data Records to UNIIIC and STL's Prosecution) STL-11-01/T/TC (6 May 2015) (TC) [104]. ↩