Also known as: errors in fact · mistake of fact
Written by attorneys · grounded in primary & secondary sources — see below
A mistaken belief about an existing fact, as opposed to a misunderstanding of legal rules.
Ezra Eastman confronted an intruder he believed was unlawfully entering his home. The intruder was in fact a police officer executing a valid warrant. Because Ezra's belief rested on a reasonable mistake of fact not caused by his own fault, he retained the privilege to use reasonable force in defense.
Emmett Egan's will left his donor-advised account at Helping Hands Fund to one charity. Clear and convincing evidence showed he had opened a second account under a different email address and always treated both as a single charitable resource. The court reformed the will to include the omitted account because a mistake of fact had affected the specific terms.
Select any source to read its text and confirm it supports the definition.
Elena Estrada executed a trust naming one beneficiary for her retirement account. Extrinsic evidence proved she had intended both accounts to pass together and that the omission resulted from a mistake of fact about the number of accounts. The court reformed the instrument to conform to her proven intention.
Enzo Eastwood sold a cow to Elliot Edmonds believing the animal was barren. Both parties shared the same mistaken belief about an existing fact. When the cow proved fertile, the mutual error of fact allowed rescission of the contract.
Ethan Evans obtained a warrant describing a residence by a detailed list of items to be seized. The list was omitted from the copy given to the occupant. The officer's reasonable mistake of fact about the warrant's facial completeness supported qualified immunity for the search.
Everest Holdings and Empire Logistics contracted for aluminum using a pricing formula tied to a particular crude-oil index. Both parties shared an erroneous belief about how the index would reflect existing market conditions. The shared error permitted rescission of the contract terms.
An error in fact excuses liability when it negates the purpose, knowledge, belief, recklessness, or negligence required for a material element of the offense. The defense succeeds if the defendant's mistaken belief about an existing fact means the prosecution cannot prove the required mental state beyond a reasonable doubt.
Supporting sources
Reformation requires clear and convincing evidence that a mistake of fact or law affected specific terms of the document and that the donor's true intention differed from the written text. Direct evidence of intention contradicting the plain meaning may be considered along with other extrinsic evidence.
Supporting sources
No. An entrant remains liable for trespass even under a reasonable mistake of fact about boundaries or ownership unless the possessor induced the mistake. The rule places the risk of third-party errors on the person who enters the land.
Supporting sources
…time the contract is made, but must have been known to one or both of the parties. Where there is no warranty, there can be no mistake of fact when no such fact exists, or, if in existence, neither party knew of it, or could know of it; and that is precisely this case. If the owner of a Hambletonian horse had speeded him, and was…