Dealings with nonparty witnesses should be courteous and designed to leave the witness with an appropriately good impression of the legal system.
Specifically, a lawyer who manifests professional courtesy and civility will have a copy of the notice of deposition, or a substantial equivalent, served with the subpoena, and will serve a copy of the subpoena upon all counsel.
Haw. G. Prof'l. Crtsy. & Civ. 9