Under Zubulake V (Zubulake v. UBS Warburg, S.D.N.Y. 2004), key players are the people whose documents are most likely to be relevant to a matter. Identifying them and recording why each is a key player is the firm's preservation responsibility once litigation is reasonably anticipated.
Why key-player identification matters
Courts evaluate a firm's preservation efforts in part by asking whether it correctly identified the people whose records matter. A key-player rationale captures the basis: what role the person held during the relevant period, what they decided, what they communicated. Sedona Conference Guideline 6 recommends documenting this rationale as part of the hold record.
Hintyr requires a key-player rationale for every custodian added to a legal hold. See Adding custodians for guidance on writing a defensible rationale.