T. James Cass

Manager, Review Services and Senior Counsel


July 7, 2021


Custodian interviews are an important and necessary part of the identification phase of an eDiscovery project. Early interviews are necessary to develop a proportionate and defensible discovery plan. 


The purpose of the interview is to:


  • identify the cast of characters,
  • the relevant time periods,
  • the potential sources of electronically stored information (ESI), and
  • confirm that the individuals understand the legal hold requirements.

If custodian interviews are not done there is a risk that the relevant information won’t be preserved and collected or conversely that too much data is preserved and collected.  Either way, this could result in extra costs being incurred.


The custodian interview should include general questions about the employee’s history with the enterprise as it relates to the issues in the investigation/dispute.  The objective of these questions is to obtain an understanding of the scope and timing of the employee’s role.  It should also include the details about the employee’s reporting structure, including direct reports, peers, and superiors.


In addition, the questions should elicit information about who the employee interacted with – both internally and any opposing parties.  This can assist in determining the key custodians for the other party to the dispute.


With respect to the potential sources of ESI, it is important to ask employees about the software and computer equipment used during the relevant time period, and where they saved the ESI.  This includes where the equipment is currently located, whether records were stored locally or on servers, and if possible, any naming conventions used for the key records which were created.


By asking open questions there is a greater chance of obtaining more complete information about where potentially relevant ESI is located.  Ask follow-up questions as people often forget some details or past practices.  It is important to ask about any code words, acronyms and abbreviations which were used with respect to the matter.  This information will help in the analysis of the ESI and assist with the understanding of the records during the review.  It is vital, from a defensibility position, to verify the answers that are provided.


Not every employee in your enterprise will require a face-to-face interview.  A questionnaire can be used to determine the extent to which an employee has any potentially relevant ESI in relation to the dispute or investigation.  For those employees with little or no involvement, this initial questionnaire might be sufficient.  For key employees, however, a custodian interview will definitely be required in addition to a written questionnaire.


Through the use of custodian interviews and questionnaires, the enterprise and its counsel will be able to better determine and narrow the scope of ESI that needs to be collected.  It goes without saying that one of the most important steps is to carefully document the custodian interview process.  With proper documentation, the defensibility of the process and the decisions on what data was preserved and collected can properly be asserted.


T. James Cass is Manager, Review Services and Senior Counsel at Heuristica Discovery Counsel LLP.  Heuristica has offices in Toronto and Calgary and is the sole national law firm whose practice is limited to eDiscovery and electronic evidence.  Heuristica has considerable experience in investigations and disputes and recently became the first law firm in the world to be awarded RelativityOne Silver Partner status.