Judicial notice of facts can be broken down into three categories: adjudicative, legislative, and background. Although the distinction was perhaps first recognized by Professor Thayer, it was not until 1942 that Professor Davis coined the terms “legislative” and “adjudicative” facts:
When a court or an agency finds facts concerning the immediate parties -- who did what, where, when, how, and with what motive or intent -- the court or agency is performing an adjudicative function, and the facts so determined are conveniently called adjudicative facts. When a court or an agency develops law or policy, it is acting legislatively; the courts have created the common law through judicial legislation, and the facts which inform the tribunal's legislative judgement are call legislative facts.
Background facts are more difficult to distinguish because they are both adjudicative and legislative:
Courts notice without proof all, whether fact or law, that is necessarily or justly imputed to them, by way of general outfit for the proper discharge of the judicial function. . . . Among such things are the ordinary meaning, construction, and use of vernacular language; the ordinary rules and methods of human thinking and reasoning; the ordinary data of human experience, and judicial experience in the particular region; the ordinary habits of men.
Clearly, the courts could not function if proof was needed on the meaning of every word uttered by a witness that bore upon the outcome of a case. In a negligence case involving a motor vehicle, there is no need to offer proof as to the meaning of the word "car" or its dangerous nature if improperly handled, because both judge and jury assign meaning from their daily exposure as both drivers and pedestrians. Given the nature of such facts, it would be impossible to propose a rule that would govern them.
At the other extreme, adjudicative facts deal with the dispositive facts of the case which are in controversy between the parties; as Professor Davis explained: "who did what, where, when, how, and with what motive or intent." Courts are extremely hesitant to take judicial notice of such facts because they bear directly on the rights of the parties. This is based on the belief that in an adversarial legal system it is best to allow the parties to establish the facts that are essential to their cases:
The reason we require a determination on the record is that we think fair procedure in resolving disputes of adjudicative facts calls for giving each party a chance to meet in the appropriate fashion the facts that come to the tribunal's attention, and the appropriate fashion for meeting disputed adjudicative facts includes rebuttal evidence, cross-examination, usually confrontation, and argument (either written or oral or both). The key to a fair trial is opportunity to use the appropriate weapons (rebuttal evidence, cross-examination, and argument) to meet adverse materials that come to the tribunal's attention.
Because parties are attempting to reconstruct a particular course of events that occurred in the past, a court will only take judicial notice of operative facts when an adjudicative fact is beyond dispute.