The Federal Rules of Civil Procedure have very liberal discovery provisions. Before the rules were adopted in 1938, plaintiffs essentially had to prove their case before filing suit. See notice pleading. The Federal Rules changed that such that under the rules' liberal discovery approach, plaintiffs who strongly suspect that they were wronged can file a lawsuit, even if they do not have solid evidence. Additionally, during discovery, they can force the defendant to give them evidence that they can use to build their case.
Discovery under the Federal Rules is very broad. According to Rule 26(b)(1), "Parties may obtain discovery regarding any non-privileged matter that is relevant to any party's claim or defense." The federal rules also provide several tools that can be used to get information from other parties, including interrogatories, depositions, and requests for admission. A party may also compel other parties to give them access to documents, real property, or other things for review or testing. See Rules 26-37.
Complying with discovery rules is particularly difficult and expensive for institutional defendants because it takes time and incurs legal fees. This difficulty is somewhat mitigated by rules allowing defendants to simply grant plaintiffs access to their records, effectively telling them "if you want it, find it for yourself." See Rule 33. This does not, however, reduce the legal expenses involved in reviewing and responding to discovery requests. Depositions are particularly expensive.
In most states, an attorney’s work product is not obtainable through disclosure. This is an unqualified immunity regardless of subject matter. “Material prepared for litigation” is not absolutely protected, however. That generally means that work prepared by non-attorneys for the litigation would be discoverable. For example, in People v. Kozlowski, 11 N.Y.3d 223 (2008), notes from director interviews taken during a law firm’s internal investigation were not protected from a subpoena filed by the defendants.
Discovery rules vary by jurisdiction.
[Last updated in September of 2022 by the Wex Definitions Team]