Judicial Notice is a rule of evidence that allows a fact to be introduced into evidence if the truth of that fact is so notorious or well known that it is cannot be refuted. Matters admitted under judicial notice are accepted being formally introduced by a witness or other rule of evidence, and even if one party wishes to lead evidence to the contrary.

For example, in an insurance claim for spoiled food from the August 14, 2003 blackout in north-east North America, the plaintiff would not be required to call witnesses to prove that there was no way to get power to run their freezers during the period in question.

A famous example of the use of judicial notice was Abraham Lincoln's famous "Almanac Case". When a witness claimed that the moon was directly overhead when he saw a murder, giving enough light to see clearly, Lincoln introduced an almanac into evidence to show that at the time in question, the moon was just above the horizon. The court accepted the information in the almanac despite evidence to the contrary from the witness.

Legal disputes about foreign affairs are generally settled by judicial notice by obtaining the information directly from the office of the Secretary of State (in the United States) or the Foreign Secretary (in the United Kingdom). For example, if a litigant in an extradition hearing attempted to argue that Israel was not a sovereign state, a statement from the Secretary of State that the U.S. recognized Israel as a sovereign state would settle the issue and no evidence could be led to the contrary.

Recently, Court of Appeal decisions regarding the legal rights of detainees of Guantanamo Bay took judicial notice of the fact that Cuba had no sovereignty over the U.S. naval base in that location despite claims by the United States goverment that it was Cuban territory and not subject to the application of United States law.