Discovery is the factfinding process in civil litigation in which the parties to a lawsuit exchange requests for the production of documents and other tangible items (requests for production); written questions to be answered under oath (interrogatories); witness testimony to be provided by oral deposition; disclosures that may be required under the applicable rules without request from an opposing party; and requests or subpoenas to third-parties (who are not parties to the lawsuit) for the production of documents or tangible things, or the giving of testimony by oral deposition, for example.

The discovery process is one of the most important, time-consuming, and often expensive parts of civil litigation. The discovery process—including the scope of discovery requests, deadlines to respond, and privileges from responding—are usually governed by the state or jurisdiction’s rules of civil procedure or code of civil procedure. For example, in federal court discovery is governed by the Federal Rules of Civil Procedure.

In Pennsylvania, the discovery process in civil litigation is governed by the Pennsylvania Rules of Civil Procedure. These rules outline the methods and scope of discovery, including the exchange of documents, answering interrogatories, and conducting depositions. Parties may request the production of relevant documents and items, pose written questions to be answered under oath, and take oral depositions of witnesses. Additionally, certain disclosures may be required without a formal request. The rules also cover the issuance of subpoenas to third parties for both documents and depositions. Discovery is designed to prevent surprises at trial and allow both sides to prepare their cases effectively, but it can be complex and costly. Privileges and protections, such as attorney-client privilege or work product doctrine, may limit the scope of discovery. Deadlines for responding to discovery requests are set by the rules, and failure to comply can result in sanctions. In federal cases, the Federal Rules of Civil Procedure apply, which may differ from Pennsylvania's rules.