In civil procedure, during the discovery phase of litigation, a party to a lawsuit may request that another party provide any documents that it has that pertain to the subject matter of the lawsuit.
The responding party is required to furnish copies of any documents that are responsive to the request, except for those that are legally privileged.
The responding party also can submit a response to the requestor explaining why the documents cannot be produced.
However, the requestor then may file a motion to compel discovery to ask the court to order the responding party to produce documents.
The rules governing requests for the production of documents vary from jurisdiction to jurisdiction; in the U.S. Federal court system, such requests are governed by Rule 34 of the Federal Rules of Civil Procedure.