The United States legal systems, both state and federal, are characterized by liberal discovery policies. The Federal Rules of Civil Procedure provide for a broad disclosure in litigation in the federal courts, permitting parties to seek discovery of "any nonprivileged matter that is relevant to any party's claim or defense and proportional to the needs of the case, considering the importance of the issues at stake in the action, the amount in controversy, the parties' relative access to relevant information, the parties' resources, the importance of the discovery in resolving the issues, and whether the burden or expense of the proposed discovery outweighs its likely benefit." Importantly, "[i]nformation within this scope of discovery need not be admissible in evidence to be discoverable." The "discovery provisions are to be applied as broadly and liberally as possible," according to the US Supreme Court. The states have adopted similarly generous disclosure rules.
Under the Federal Rules of Civil Procedure, initial disclosures are made by the parties on the commencement of a lawsuit. The parties have an ongoing duty to "supplement" their disclosures as new information becomes available that is responsive to discovery requests, subject, of course, to the attorney-client privilege and work product protection. Except in the case of a criminal trial, the parties are also entitled to take depositions of the parties. Depositions of other witnesses, including witnesses chosen to represent corporations or other entities, are commonplace, as are written interrogatories, requests for admission of facts, and requests for the production of documents and things or the right to inspect premises or to undertake physical examinations of a person.
Objections to the scope and substance of discovery may limit the duty to disclose; such objections may include invocations of the attorney-client privilege and work product doctrine, as well as lack of relevance and undue burden. Non-parties may also be subpoenaed or otherwise required to turn over documents or things, again subject to the claims of privilege or work product.
Discovery-related disputes are generally resolved by the courts on motions for protective orders or motions to compel. Failures to comply with discovery-related court orders may be sanctioned by the court.
Evidence may be sought from non-US entities or persons pursuant to the Convention on the Taking of Evidence Abroad in Civil or Commercial Matters (also called the Hague Evidence Convention) or pursuant to other conventions of which both the United States and the other nation are signatories. In the case of litigation involving parties that are beyond the court's subpoena powers, as prescribed by the Federal Rules of Civil Procedure, the court may issue and serve a subpoena directed to a US national or resident who is in a foreign country. Conversely, a federal statute allows a party to a legal proceeding outside the United States to apply to a court in the United States to obtain evidence for use in the foreign proceeding.
