An order compelling a non-party deponent attorney to disclose the identity of an expert non-witness consultant he hired in a prior case was not an appealable collateral order because it related to the subject matter of the plaintiff’s suit against that expert for disclosing confidential material without permission.  But the court treated the appeal as a writ petition since the issue would otherwise evade effective review.  The identity of the expert non-witness consultant is entitled to absolute work product protection only if the attorney makes a preliminary showing that revealing the consultant’s identity would disclose the attorney’s tactics, impressions, or evaluation of the case.  No such showing was made here.  So in this case only qualified work product privilege.  The trial court did not abuse its discretion in ordering disclosure since plaintiff had no other means of identifying the defendant who had disclosed its confidential material.  By contrast the deponent attorney will suffer little harm from disclosure of the consultant’s identity.