Judicial notice is a rule of the law of evidence that allows at the instance of a party the introduction and acceptance of well known and notorious facts that cannot be challenged as evidence without formal proof through witness. Matters deserving judicial notice can be admitted even if the opposing side wishes to lead evidence to the contrary.
Article II of the Federal Rules of Evidence deals with judicial notice in federal courts, and this article has been borrowed or taken verbatim by many U.S. States. FRE 201(b)) permit judges to take judicial notice of two categories of facts:
• Those that are "generally known within the territorial jurisdiction of the trial court" or
• Those that are "capable of accurate and ready determination by resort to sources whose accuracy cannot reasonably be questioned”.
Judicial notice may either be permissive or mandatory. Though the Federal Rules of Evidence do not specify the type of facts that would fit into one category or the other, yet it has been laid down in judicial decisions that courts must take mandatory judicial notice of federal and state public laws; official regulations of federal, state and local governments and treaties by and between governments.
When it is mandatory the court must take judicial notice of the fact tendered.
When it is permissive, the court may at its discretion either allow or reject the request for taking judicial notice. In case the court turns down the plea for judicial notice, the fact offered has to be introduced through witness in witness action.
The effect of the court taking judicial notice varies in civil and criminal actions. In civil proceedings the fact taken judicial notice of stands conclusively proved and the opposing party would be prevented from leading evidence to the contrary. However, in criminal trials, the jury need not necessarily adopt or accept such facts taken judicial notice of as sacrosanct. The defendant is at liberty to challenge any fact offered tending to incriminate him regardless of judicial notice taken of the same and can tender evidence to refute even judicially noticed fact.