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 Wisconsin, the discovery process in civil litigation is governed by the Wisconsin Rules of Civil Procedure, which are found in Chapters 804 to 807 of the Wisconsin Statutes. These rules outline the procedures for parties to obtain evidence from each other and from third parties. The discovery tools include requests for production of documents, interrogatories (written questions to be answered under oath), depositions (witness testimony given under oath before trial), and requests for admissions. Wisconsin law also requires initial disclosures to be made without a formal discovery request, which typically include the exchange of relevant information and documents that the parties intend to use in the case. The scope of discovery is generally broad, allowing parties to obtain any non-privileged material that is relevant to any party's claim or defense and proportional to the needs of the case. However, there are limits to prevent abuse of the discovery process, such as privilege (e.g., attorney-client privilege), privacy concerns, and undue burden or expense. Deadlines for responses and objections to discovery requests are also set by these rules, and failure to comply with discovery obligations can result in sanctions by the court.