Investigations and litigation frequently require accountants, technologists, public relations advisers and industry experts. Whether their work is protected depends on how they were engaged.

The functional equivalent doctrine. Communications with a consultant who is the functional equivalent of an employee — integrated into the organization, performing a role an employee would otherwise perform, with authority to act — may be privileged on the same basis as employee communications.

Agents assisting counsel. A consultant retained by counsel to enable the provision of legal advice, on the interpreter model, is within the privilege. The engagement must be by counsel, in writing, stating that purpose, and the consultant must actually report to counsel.

Work product is broader and covers materials prepared by or for a party or its representative in anticipation of litigation, including consultants, regardless of the privilege analysis.

Public relations advisers. Protection is uncertain and generally denied where the adviser’s role is to manage reputation rather than to assist in legal advice. Assume communications are discoverable.

Practical structure. Retain through counsel; state the purpose; direct reporting to counsel; mark deliverables; limit distribution; and keep the consultant’s business advice in a separate stream from the litigation work.