In U.S. legal procedure, each party to a lawsuit

Lawsuit

A lawsuit or "suit in law" is a civil action brought in a court of law in which a plaintiff, a party who claims to have incurred loss as a result of a defendant's actions, demands a legal or equitable remedy. The defendant is required to respond to the plaintiff's complaint...

 has the duty to disclose certain information, such as the names and addresses of witness

Witness

A witness is someone who has firsthand knowledge about an event, or in the criminal justice systems usually a crime, through his or her senses and can help certify important considerations about the crime or event. A witness who has seen the event first hand is known as an eyewitness...

es, and copies of any documents that it intends to use as evidence, to the opposing party. This duty is subject to certain exceptions, as outlined in the Federal Rules of Civil Procedure

Federal Rules of Civil Procedure

The Federal Rules of Civil Procedure govern civil procedure in United States district courts. The FRCP are promulgated by the United States Supreme Court pursuant to the Rules Enabling Act, and then the United States Congress has 7 months to veto the rules promulgated or they become part of the...

; furthermore, the rules applicable in state courts vary from state to state.

See also

• Duty of candor
  Duty of candor
  -UK Public Law:The Duty of Candour is the concept a public authority should not seek to win the litigation at all costs butto assist the court in reaching the correct result and thereby to improve standards in public administration....
  
  
• Information disclosure statement
  Information disclosure statement
  An information disclosure statement refers to a submission of relevant background art or information to the United States Patent and Trademark Office by an applicant for a patent during the patent prosecution process...
  
  (U.S. patent law)