Wis JI-Civil 3072

You are instructed that a mutual mistake of fact exists where both parties to a contract

are unaware of the existence of a past or present fact material to their agreement, or where

both parties believe a fact exists which is actually non-existent. The unawareness or belief,

however, must arise from a lack of knowledge of the possibility that the fact may or may not

exist. If the parties are conscious or aware of, or alerted to, the possibility that a fact does or

does not exist, and they waive any inquiry or make no investigation with respect to it, they

are not legally mistaken with respect to it.

If there was conscious doubt or uncertainty on the part of the parties as to the

existence or non-existence of a fact or situation, and the parties reached an agreement under

such circumstances, it is considered that it was their intention and contemplation to accept

and compromise the consequences of the doubt and uncertainty, and they would not then be

acting under mutual mistake of fact.

A mistake to be mutual must involve both parties. A mere mistake on the part of one,

in the absence of fraud on the part of the other, will not avoid a contract obligation.

[A mutual mistake of fact exists when both parties believe and rely on medical

representation as to the nature and extent of injuries, which later prove to be erroneous, even

though such representations were made in good faith. The representations, however, must

refer and apply to existing facts and not be mere expressions of opinion as to future events or

development.]