Discovery under the U.S. law is the pre-trial phase in a lawsuit in which each party can request documents and other evidence from other parties and can compel the production of evidence by using a subpoena or through other discovery devices, such as requests for production of documents, and depositions.
Discovery therefore includes (1) interrogatories; (2) motions or requests for production of documents; (3) requests for admissions; and (4) depositions.
Many states have adopted discovery procedures based on the federal system; some closely adhere to the federal model, others not so closely. Some states take an entirely different approach to discovery. The law relating to discovery for the various states of the United States can be found at the following links.