Mutual Mistake
Mutual mistake is the doctrine for when BOTH sides got the same fact wrong at the moment they signed, and that shared mistake reaches the heart of the deal.
8. Mutual Mistake
If both parties held a mistaken belief at the time the contract was made, the contract may be voidable by the adversely affected party.
- A contract is voidable on the ground of mutual mistake if:
- The mistake relates to facts in existence at the time the contract was made;
- The mistake relates to a basic assumption underlying the contract;
- The mistake has a material effect on the agreed exchange of performances; and
- The adversely affected party did not bear the risk of the mistake.
- The mutual mistake must involve a fact in existence when the contract was made. The doctrine does not void contracts based on mistaken predictions about the future or mistakes merely about the value of the goods or services that are the subject of the contract.
- The mistake cannot relate to a peripheral contract term or have a minor effect on performance.
- A party bears the risk of a particular mistake if the agreement allocates that risk to them or if that party is aware at the time of making the contract that they have only limited knowledge of the facts to which the mistake relates but treat that knowledge as sufficient (“conscious ignorance”). A court may also allocate risk of the mistake to the party that has more access to information about the facts to which the mistake relates.
- A “scrivener’s error” (a clerical mistake in recording the parties’ agreement) does not void the contract. Instead, the record is reformed to reflect the parties’ agreement.
- The usual remedy for mutual mistake is rescission or voiding of the contract.
- The Nevada FLE does not test the doctrines of impossibility, impracticability, and frustration of purpose, which cover unexpected future events rather than mistake about facts in existence when the contract was made.
Mutual mistake is for when both sides got the same fact wrong at signing and that shared mistake reaches the heart of the deal. The contract is not void but voidable, and only by the adversely affected party, if a closed four-part test is met.
Mutual mistake is the doctrine for when both sides got the same fact wrong at the moment they signed, and that shared mistake reaches the heart of the deal. The result is not that the contract is void, an empty nothing. It is that the contract is voidable, and only by the party the mistake hurt, the adversely affected party. That distinction matters because a voidable contract stands until the hurt party elects to undo it.
- 1The mistake must relate to a fact in existence at the time the contract was made.
- 2The mistake must relate to a basic assumption underlying the contract.
- 3The mistake must have a material effect on the agreed exchange.
- 4The adversely affected party must not have borne the risk of the mistake.
Miss any one of the four and the contract holds. The first part does the most filtering, so read it carefully. The fact has to already exist when the parties sign. A mistaken prediction about the future is not a mistake of existing fact, and neither is a mistake merely about the value of the goods or services. A buyer who pays full price for a painting both sides believe is a genuine old master, when in fact it is a worthless modern copy, has a mistake about an existing fact, the painting's actual identity, not a bet on the future. But a buyer who simply guessed the market wrong, or who hoped the thing would appreciate, has no mutual-mistake claim at all.
The fourth part is the other big filter: risk allocation. A party bears the risk, and therefore cannot void, if the agreement assigns that risk to them, or through conscious ignorance, meaning the party knew at signing that their knowledge of the relevant facts was only limited but treated that limited knowledge as good enough anyway. A court may also place the risk on the party with greater access to the information. A party who bore the risk is stuck with the deal. For a genuine mutual mistake, the usual remedy is rescission, voiding the contract.
One wrinkle students miss: a scrivener's error, a clerical slip in writing down a deal the parties actually agreed to, does not void anything. The remedy there is reformation, fixing the writing to match the real agreement, not rescission.
This is about facts wrong at formation, not later events. Impossibility, impracticability, and frustration of purpose are off the table on this exam.
fact, basic, material, risk: the four-part closed test, all four required, and only the adversely affected party can void.
Run them in order: existing fact (not a prediction, not value), basic assumption, material effect, and the voiding party did not bear the risk.
Three quick kills for a mutual-mistake claim: a mistaken prediction about the future, a mistake merely about value, or a party who bore the risk (allocated by the deal, conscious ignorance, or superior access).
Any one of these and the contract holds.
Reform, don't rescind, for a scrivener's error.
A clerical slip in recording an agreement the parties actually reached is fixed by reformation, not voided.
Rescission is the remedy for a true mutual mistake.
A coin dealer and a collector both believe a particular gold coin in the dealer's case is an ordinary modern strike, and they agree on a price set for an ordinary coin. Neither party knows that the coin is in fact a rare proof issue worth many times the agreed price. After the sale, the dealer learns the truth and seeks to void the contract for mutual mistake.
Assuming the dealer did not bear the risk, all four parts are met and the contract is voidable by the dealer, the adversely affected party, with rescission as the remedy. Now suppose the writing correctly reflected a coin both sides knew was rare, but a typist mis-entered the price. That is a scrivener's error. The contract is not voided; the writing is reformed to the price the parties actually agreed on.
An option that resolves the case on impossibility, impracticability, or frustration of purpose, or otherwise frames the problem around an unexpected future event.
Those doctrines are excluded from exam scope and cover future events; mutual mistake turns on a fact wrong at formation, so resolve the case on the four-part mistake test and eliminate the future-event doctrine.A true but insufficient fact: the parties shared a belief, the thing turned out worth more or less than expected, or both sides were equally unaware. Often sympathetic.
Check the threshold: the mistake must be about a fact in existence at formation, not a prediction or a value misjudgment, and a party who bore the risk cannot void despite shared ignorance.An option that misstates the element or remedy: calls the contract void rather than voidable, gives rescission for a scrivener's error, or requires the other party's consent to void.
A genuine mutual mistake makes the contract voidable by the adversely affected party alone; a scrivener's error is reformed, not rescinded.An absolute answer, for example that an “as is” sale can never be rescinded or that any shared mistake voids the deal.
Distrust the universal; the outcome turns on the four-part test and risk allocation, not on a categorical rule about a sale label.the stem hands you two parties who shared the same wrong belief when they signed, and the belief goes to the heart of the deal.
The instant you see a shared mistake, run the four-part check in order.
is it a fact that already existed at signing, or is it really a prediction about the future or just a misjudgment about value?
If it is a prediction or a value guess, the claim fails before you go any further.
is it a basic assumption the deal was built on?
does it materially skew the exchange, or is it peripheral and minor?
did the party seeking to escape bear the risk, by agreement, by conscious ignorance (knew their knowledge was limited but treated it as enough), or by having superior access to the facts?
If all four line up, the contract is voidable by the adversely affected party and the remedy is rescission.
Two off-ramps to watch: if the facts describe a clerical slip in writing down a deal the parties actually reached, the answer is reformation, not rescission; and if an option resolves the case on impossibility, impracticability, or frustration of purpose, eliminate it, that is excluded from scope and signals a future-event problem, not a mistake.
An art dealer and a private collector agreed on a price for an oil painting that both believed was an anonymous nineteenth-century decorative piece. The price reflected that shared belief. Neither party knew at the time of the sale that the painting was in fact a signed work by a noted master, worth many times the agreed price. Both had examined the painting and neither had any reason to suspect its true origin, and the written agreement said nothing about who would bear the risk of a misidentification. After the sale, the dealer discovered the painting's true authorship and sought to undo the deal.
Is the dealer likely to succeed in voiding the contract for mutual mistake?
A grower and a produce wholesaler signed a contract for the grower's entire upcoming harvest of a specialty fruit at a fixed price per crate. Both parties expected, based on the prior season, that prices would stay strong and that the harvest would be ordinary in size. After signing, market demand collapsed and an unusually heavy yield drove the going rate far below the fixed price, leaving the wholesaler badly overpaying. The wholesaler asked a court to undo the contract, arguing that both sides had been mistaken about what the season would bring.
Is the wholesaler likely to prevail on a mutual-mistake theory?
A rancher offered to sell a fenced parcel “as is, sight unseen below the surface,” and a buyer agreed, both believing the land was ordinary grazing pasture. The buyer knew he had not surveyed or tested the parcel and told the rancher he was comfortable going ahead on what little he knew rather than spend money investigating. After closing, the buyer learned the subsurface was unsuitable for the irrigation well he had hoped to drill, making the parcel far less valuable to him. The buyer sued to rescind for mutual mistake, noting that the rancher had been just as unaware of the subsurface condition as he was.
Is the buyer likely to obtain rescission for mutual mistake?
A supplier and a restaurant negotiated and orally agreed on a price of fourteen dollars per case for a weekly produce delivery. When the supplier's assistant typed up the written contract, she mistakenly entered the price as forty dollars per case. Both parties signed without catching the error. After the first invoice arrived, the restaurant pointed out that the writing did not match the price the parties had actually agreed on, and the supplier conceded the typed figure was a slip. The restaurant asked a court for relief.
What is a court most likely to do?
A jeweler and a buyer agreed on a price for a ring that both believed held a genuine natural emerald of a particular grade, a belief central to the price they set. In fact, unknown to either party at the time, the stone was a synthetic of far lower worth. Neither party had reason to doubt the stone, and nothing in their agreement assigned the risk of a misgraded stone to either side. The buyer, who paid a natural-emerald price, learned the truth and wishes to escape the deal, while the jeweler insists the sale is final.
Is the buyer entitled to void the contract?